Exchange and DDNS? Possible?


Recommended Posts

I'm sure all you get is a DNS address resolved to an IP with any Dynamic DNS service.

The only way I can think is to have an alias such as mx0.example.com which is a CNAME of test.no-ip.org. mx0.example.com will then need to be a record itself. I guess you could also just have test.no-ip.org as your only MX record.

My first thought though would be to test the possibility of receiving and sending on port 25. I would have thought most domestic ISP's will block this communication.

SK[' timestamp=1343722926' post='595047579]

I'm sure all you get is a DNS address resolved to an IP with any Dynamic DNS service.

The only way I can think is to have an alias such as mx0.example.com which is a CNAME of test.no-ip.org.

My first thought though would be to test the possibility of receiving on port 25 and sending. I would have thought most domestic ISP's will block this communication.

well i think there was also a way around this for using a ddns fqdn as a web server from your home rite? i imagine there is something also like this for stmp (port 25, like you comment)

Can't think of a way as every other SMTP server in the world will be expecting to speak to your server on port 25. If your ISP block it then your pretty much stuffed. DynDNS offer some sort of mail feature though.

As I said test the connectivity first before implementing a solution that won't work. I host my three sites on my home network with the same Dynamic IP being used as an alias. It works fine. I know though that port 25 is blocked outbound as there is no mail functionality working. Kinda annoying as I run forums. Still, they are dead ones these days and are only really used for reference.

SK[' timestamp=1343722926' post='595047579]

I'm sure all you get is a DNS address resolved to an IP with any Dynamic DNS service.

The only way I can think is to have an alias such as mx0.example.com which is a CNAME of test.no-ip.org. mx0.example.com will then need to be a record itself. I guess you could also just have test.no-ip.org as your only MX record.

My first thought though would be to test the possibility of receiving and sending on port 25. I would have thought most domestic ISP's will block this communication.

Not all do. Time Warner for example leaves the port open but adds its residential IP blocks to one or more DNS Block lists, so that all mail that comes from them gets marked as spam by receivers who check against said lists.

I'd imagine using something like DDNS probably would cause a similar issue. Though idk.

If what you want to do is accept incoming mail, yeah not too many issues there - get a MX record pointed to where you want to accept mail. That is about it.

Where the problem comes in is sending, as mentioned already -- most of the major players will block you from sending them email from a dynamic IP. Even if not using a block list, do you have a valid PTR for this IP - not going to accept mail from you.

So if what you want to do is send mail to your friend billy on his HOME smtp server, then sure go for it. If what you want to do is send actual production email that your sure is going to get there. Not so much, not to any of the major player domains, or any companies doing any sort of decent filtering.

  • 5 months later...

I run my own exchange server. Receiving emails are OK but sending gives an error. Tested via Exchange Connectivity and its says that no PTR Record available for the IP. Any solution to this?

by the way, I use Zerigo as my Dynamic DNS.

receiving you will be fine, it is always the sending. Many isps have closed out bound port 25 traffic outside of their network when on their dynamic ip network. Many spam filters have excluded dynamic range from being able to get through. How do you get around the world denying you?

The option would be to send through a mail host, you can use your isp mail host, but they may have a sending limit.

receiving you will be fine, it is always the sending. Many isps have closed out bound port 25 traffic outside of their network when on their dynamic ip network. Many spam filters have excluded dynamic range from being able to get through. How do you get around the world denying you?

The option would be to send through a mail host, you can use your isp mail host, but they may have a sending limit.

Using my ISP Mail Host is a great idea. I don't mind if they have sending limit. Do I only require to get the SMTP for the ISP? or what else info is required?

yeah sure there are lots of people that provide FREE email servers for you to send your mail through :rolleyes:

If you want/need to send email - then you have to be ready to show your not some random box on the net sending spam. No business that needs to use email is going to be on a dynamic IP. Your also going to be able to setup a PTR because again your not a on dynamic IP and your ISP provides you the ability to change the name the IP resolves too. Only the owning ISP can do this, arin controls who where netblocks point for dns here in the US, other parts of the world would be other orgs, lacnic, ripe, apnic, afrinic

Shoot more and more companies are giving up on running their own mail and doing it in the cloud themselves - not even running their own email servers any more. Or contract out companies to be the front man to their exchange boxes - where this other network sends and recv the mail, and exchange gets mail from this company, and sends all email through them "smart host"

Here is the thing - running your own email server on a home connection for anything other than a hobby or for you to get mail from to some bs domain that gets a couple of mails a day and sends a few a day through your isp email server is nothing more than an exercise in futility.

More likely than not your prob just going to end up running a spam machine anyway ;)

edit: What version of exchange are you running? Look up how to setup smarthost. Keep in mind that many isp will not allow you to send mail from other than your email address, ie say account is [email protected] -- many will not allow you to send mail through their servers that say the email is from [email protected]

SMTP you will need as well as your account info to be able to authenticate and send mail through. You will need to send mail as this account though...the mail header needs to show this for your recipients to be able to receive mail. Unless they just do a ip check (which may be the case), but if they do any sort of resolve and the ip doesn't match the header host it won't make it through. There is a lot that goes on to verify authenticity of the sender in a spam filter.

edit: What version of exchange are you running? Look up how to setup smarthost. Keep in mind that many isp will not allow you to send mail from other than your email address, ie say account is [email protected] -- many will not allow you to send mail through their servers that say the email is from [email protected]

am using Exchange Server 2013 over Windows server 2008 R2 (which is a DC as well). My ISP is Saudi Net (worst ISP in the entire middle east with no support at all). Cant even request for PTR. Tried the SMTP for them but still not working, maybe am not configuring Exchange Server properly.

SMTP you will need as well as your account info to be able to authenticate and send mail through. You will need to send mail as this account though...the mail header needs to show this for your recipients to be able to receive mail. Unless they just do a ip check (which may be the case), but if they do any sort of resolve and the ip doesn't match the header host it won't make it through. There is a lot that goes on to verify authenticity of the sender in a spam filter.

I tried tons of ways but none work. Web Server was way easy configuring compared to exchange server :/

"Cant even request for PTR."

I don't know of any ISP that would setup PTR of a dynamic IP other than the generic ones you get.. For example

;; QUESTION SECTION:

;xx.xx.13.24.in-addr.arpa. IN PTR

;; ANSWER SECTION:

xx.xx.13.24.in-addr.arpa. 7200 IN PTR c-24-13-xx-xx.hsd1.il.comcast.net.

Now such a PTR might meet some filtering some domains do in the sense that it exists.. Others might reject it because its not a true reflection of the forward name.. So for example if your mail server IP is resolved via smtp.somedomain.tld, they might like the PTR of the IP that resolves to to reflect the same smtp.somedomain.tld

As I already mentioned, some ISPs won't allow their smtp servers to send mail for anything other than the account holder email address. So if your email address with your isp is [email protected] and your trying to send email from [email protected] - even if you auth with your specific account info, their server might tell you to get lost since the email address is not valid for that account.

Many ISPs don't even allow outbound on 25 from their dynamic client networks, nor allow their smtp server to send email for any other email address then what is listed on the specific account - this is to help reduce spam being sent from their network. If you have such restrictions then your only solution is to pay for a smarthost that allows you to send mail they forward on your behalf on a different port, etc. The dyndns company already mentioned provides such solutions. If you not willing to pay for such services - how are you affording exchange? ;)

If you not willing to pay for such services - how are you affording exchange? ;)

I can afford all the services, but I wanted to setup it for free at all. By the way, setting up all this was a part of my exercise. Wanted to learn about the Web hosting, Domain Controller, Email exchange. All was setup properly except this Exchange. I tried adding the PTR host in Zerigo (my Dynamic DNS service) it was done but my ISP really need to assign me a PTR record to my IP (which seems not possible for Dynamic IP Users). How about if I search for some free SmartHost providers before paying for something :rofl:

Edit: by the way, I get free license for Microsoft Products :D so trying all of them is not that bad :rolleyes:

Your not going to find a FREE smart host.. Not that I can think of - I don't even think google apps when it was free for your domains allowed that?

What would the smarthost get out of it? Other than prob blacklisted because you were using them to send spam ;)

You can study the setup of exchange without really having to send mail to all the major players.. Does your isp allow outbound of their network on 25? Simple enough to test, try connecting to a smtp server somewhere?

Cheap way you could do it is get yourself a VPS somewhere... I have a vps for $15 a year that would be more than capable of sending email for me, etc. And I can setup the PTR on the IP the host gave me. So it can be done for very cheap.

But again if all your doing is playing/learning does not matter if the major players will block you.. there are plenty of domains you can send to for testing that wont filter you.

So telnet to a smtp server on 25, can you connect - if so then your isp allows you to send outbound on 25 and could setup exchange to directly send.. Just some of the major players are not going to accept mail from you.

budman@ubuntu:~$ telnet mailin-01.mx.aol.com 25

Trying 205.188.159.42...

Connected to mailin-01.mx.aol.com.

Escape character is '^]'.

554- (RTR:DU) http://postmaster.info.aol.com/errors/554rtrdu.html

554 Connecting IP: 24.13.xx.xx

Connection closed by foreign host.

so you see my ISP allows me outbound on 25, but mail server for AOL told me to get lost ;) Because

54 RTR:DU[/url]

Cheap way you could do it is get yourself a VPS somewhere... I have a vps for $15 a year that would be more than capable of sending email for me, etc. And I can setup the PTR on the IP the host gave me. So it can be done for very cheap.

Where? can I get that too?

Will post the telnet results once I get the exact SMTP for the ISP :wacko:

smtp for the isp? Just do a dns look for any smtp server for any domain. Use aol for an example

As to a vps -- here are some listings of cheap ones

http://www.lowendbox.com/

http://lowendstock.com/

Mine is with http://buyvm.net/

This topic is now closed to further replies.
  • Recently Browsing   0 members

    • No registered users viewing this page.
  • Posts

    • Go for a Echo Dot or Pop instead. These Echo shows just advertise to you.
    • NetSpeedTray 1.3.3 by Razvan Serea NetSpeedTray is a lightweight, open-source Windows network monitor that shows live upload and download speeds directly on the Taskbar. Designed for efficiency, it quietly sits in the system tray, conserving CPU and battery with dynamic updates. It blends seamlessly with Windows 10/11, adapts to light/dark themes, and auto-positions to avoid overlaps. Features include accurate interface detection, customizable display, optional mini-graph, color coding, granular font and unit control, detailed per-interface history graphs, safe data management, and easy CSV export—bringing the network monitoring Windows forgot. NetSpeedTray key features: Lightweight & Efficient Runs quietly in your system tray without consuming resources. Features a "Dynamic Update Rate" that lowers refresh frequency when the network is idle to save CPU and battery life. Native Look & Feel Blends seamlessly with Windows 10/11 UI. Smart detection for light and dark taskbar themes ensures text is always visible. Intelligent & Adaptive Positioning Automatically finds empty space next to your system tray and shifts to make room for new icons, preventing overlaps. Seamless OS Integration Behaves like a native Windows component. Hides instantly with auto-hiding taskbar Hides when a fullscreen app is active Smart Network Monitoring Accurate by Default: Auto mode identifies your main internet connection and ignores noise from VPNs or virtual adapters. Easy Interface Selection: Switch effortlessly between Auto, All, or Selected network interfaces via intuitive radio buttons. Total Visual Customization Free Move Mode: Unlock and place the widget anywhere on your screen. Optional Mini-Graph: Real-time graph of recent network activity with adjustable opacity. Color Coding: Customize colors and speed thresholds to quickly see network status. Granular Display Control Text & Font: Adjust font family, size, weight, and alignment. Units: Automatic (B/s, KB/s, MB/s) or fixed Mbps display. Precision: Set decimal places and always show them for uniform appearance. Detailed & Intelligent History Graph Smart Scale: Logarithmic scale shows low-level traffic and large spikes clearly. Per-Interface Filtering: View speed history for specific adapters (Wi-Fi, Ethernet, VPN). Safe & Efficient Data Management: Adjustable retention, automatic cleanup, optimized database. Easy Data Export: Export raw data to .csv or save high-quality graphs for reports. NetSpeedTray v1.3.3: The Updater Fix A stabilization release that repairs a critical regression in v1.3.2: the app shipped without OpenSSL, which silently broke every HTTPS request — including the built-in update checker (the "Could not check for updates" error many of you hit). This release restores it, hardens the build so it can't happen again, and fixes a startup crash plus four other reported bugs. Changes: Fixed update checking — Resolved a critical issue that prevented the app from checking for updates ("Could not check for updates"). Fixed startup crash with Auto-Cycling — The app no longer crashes on launch after enabling Cycle display mode. Fixed incorrect network speeds on 10GbE adapters — Multi-gigabit network cards now display speeds correctly instead of being stuck at 0. Improved color coding — Default color is shown when idle, and color/threshold changes now apply immediately without restarting. Fullscreen visibility fix — The widget now correctly stays visible over fullscreen apps when Keep Visible is enabled. Improved AMD Ryzen temperature detection — More reliable CPU temperature monitoring for Ryzen processors. Cleaner upgrades — Installer now removes outdated application files during upgrades, preventing DLL/version conflicts while preserving user settings. Improved stability — Fixed potential DLL loading issues by excluding critical OpenSSL and NumPy components from UPX compression. Better settings window — Scrollbars removed and layout improved for a cleaner experience. Localization improvements — Updated translations and completed missing UI text across all supported languages. More reliable releases — Added regression tests covering recent critical fixes, bringing the test suite to 196 passing tests. [full release notes] Download: NetSpeedTray 1.3.3 | 87.9 MB (Open Source) Download: NetSpeedTray Portable | 101.0 MB View: NetSpeedTray Home Page | Screenshot Get alerted to all of our Software updates on Twitter at @NeowinSoftware
    • Why Delta Chat is the best decentralized messenger you have probably never tried by Paul Hill There is no shortage of messaging apps out there; we have WhatsApp, Messenger, and Telegram, just to name a few. While Meta has taken steps to incorporate encryption into Messenger and WhatsApp, they still leave a lot to be desired. If you are in the market for a messaging app that promotes security, privacy, and optional anonymity, you'll want to read what I have to say about Delta Chat. For those not familiar with Delta Chat, rather than relying on centralized servers as you do with Facebook Messenger, it relies on email. Essentially, it is a chat interface that feels like a messaging app, but secretly in the background, it is firing off emails. In the past, you used to have to sign in with your email account. When you sent messages to people, it would just be sending encrypted messages to their inbox, which their Delta Chat client would decrypt. When I first learned about Delta Chat, it required users to sign in with an email account, but I was pleasantly surprised upon trying it in 2026 that this is no longer a requirement, or the preferred method was to use the app. Recently, I’ve tried UAD-ng on my old Nokia 3.4 to disable most of the Google apps because the bootloader is locked, and this is the next best option. While finding replacement apps in F-Droid, I came across Delta Chat again, and it has undergone quite a big change since I last used it, with its new chatmail relays, which no longer require you to sign in to your own email account, providing anonymity, and they offer greater security. Android and Desktop Delta Chat apps. Not only does it run on my de-googled phone, but it also works on desktop computers and iOS, making it truly ubiquitous. For me, Delta Chat is a wonderful alternative messenger because it gives you more control. It supports switching between different profiles, which you can set up super quickly; you don’t register a username, you don’t register a password. The only thing you do have is a random string email address on a chatmail relay (which you don’t have to memorize). To maintain access to your profile, you just need to add a second device to your account via QR code or make a backup of your account, which you can restore later. Fail to do these, your account is gone - as it should be if you don’t want to leave accounts that could get hacked later on. My decision to block Google stuff on my Nokia was done for practical reasons; the device sucked when it launched, and it sucks even more now. The nice thing about F-Droid and the apps within is that they’re usually lightweight, free of bloat, and work well on that device. What was inconvenient for me was that it was hard to send messages from that device, say if I wanted to copy a code over to my main phone or send family members a link from that device. That’s when I decided to look at the available chat apps and saw Delta Chat. Another nice thing about Delta Chat is its notifications. Some messaging apps rely on Google’s ecosystem for notification transport on Android; however, with Delta Chat, it can use Google’s solutions if you have Play Services or MicroG installed. Otherwise, it is able to keep a background connection to the chatmail relay server so that you can get notified when you receive a message. As free software, the code of Delta Chat is open for all who want to take it and build upon it. In the future, if the developers of Delta Chat make a catastrophically bad decision and take the app in an undesirable direction, users can take the code and fork the project. This contrasts with closed-source apps from corporations that can take their products in any direction they like. By relying on free software instead of closed-source programs, you actually control your computing. I’ve spoken at length about how running this type of software is like owning your own home rather than renting it. The same applies here; if you use Delta Chat, you don’t need to worry about it going away in the future. Whether it is Telegram, WhatsApp, or Messenger, you are required to register a username and password to use these services. A major flaw in this design is that anyone can try various passwords and potentially break into your account with your complete chat history intact. Sure, there is encryption in Messenger, where you need a second PIN and two-factor authentication in Telegram, but breaches happen all the time. Unlike before, when you used to sign in to your email account to send and receive messages, the primary way to do it now is to create an account on a chatmail relay. The resulting email address is a random string followed by the name of the relay you pick. This means you can start and begin adding contacts Without a username and password, you either need to ensure you have a backup or at least one device running your Delta Chat profile. The primary way to log in on another device is to go to the settings and add a second device. Then, you’ll just scan a QR code with your new device, and it’ll log in to your account and sync all your chat history and contacts. To end users, Delta Chat just looks like any instant messenger; however, it is really sending your messages as encrypted emails to your contact. This is pretty cool from a censorship perspective, as it makes the service more difficult to block. Previously, the main way to use the app was by logging in with email, but nowadays, it’s recommended that you use chatmail relays. Chatmail relays temporarily hold messages in case your device is offline. They are cheap, simple servers that don’t store data as group states. Other information, like your name and avatar, only exists on your device and the devices of those you share your contact information with. The relays are also decentralized and operated by various groups and individuals. It is even possible to set up your own chatmail relay, but most people will want to use one hosted elsewhere. To keep your messages secure, Delta Chat uses a secure subset of the OpenPGP standard that gives you automatic end-to-end encryption. It also uses Secure-Join to exchange encryption setup information through QR-code scanning or invite links. Autocrypt is also used to automatically establish end-to-end encryption between contacts and all members of group chat, but sometime this year Autocrypt v2 will be rolled out, bringing post-quantum resistant encryption and forward secrecy. The Delta Chat FAQ is an interesting read that explains many more details about the app. Credit: Pexels Delta Chat is unique among messaging apps because it is built on email, a technology that’s decades old and isn’t going anywhere soon. What’s more is that email is not centralized either, so it’s far more difficult for any authoritarian regime to disrupt the Delta Chat app. I haven’t spoken too much about features yet, so I will do that now. Delta Chat allows you to do one-on-one chats, group chats, and create channels. It also supports file sharing and making audio and video calls when chatting one-to-one, but it’s not available for group chats right now. At the time of writing, the calling functionality is disabled and can be enabled in Settings > Advanced > Debug Calls. I have used the video calling feature, and the quality is excellent. It works over WebRTC, another open standard. The app also lets you send voice notes, enables disappearing messages, and has its own app ecosystem. I did try playing chess one time there, but it was a bit spotty; though, we did manage to complete the game with a victory for me. To add people to Delta Chat, you can either give them your Delta Chat link or your QR code to scan. These are the only ways to add users, so you won't have any spam bots bothering you. If the people you want to chat with don't have the app yet, just send them your link, and it will take them to a webpage where they can install the app and then add you. It's really quick for them to install it and get started, which is nice. Credit: Microsoft. The Majorana 2 quantum chip unveiled in 2026. I do not think quantum computers are too far out now, and I do hope that Delta Chat is able to push out Autocrypt v2 sooner, rather than later, so bad actors do not attempt to collect encrypted communications and then decrypt them in the future using quantum computers. By getting people’s messages post-quantum-safe now, users won’t have to worry when quantum computers start cracking legacy encryption. Overall, I would recommend this app to people who are already past WhatsApp and Messenger and have perhaps begun using apps like Telegram or Session. It shares a lot of characteristics with these apps and goes a lot further than Telegram in terms of security. By being based on email, it is also resistant to censorship, and the lack of a username and password makes you anonymous (if you want to be) and safe from brute force password cracking attempts. Let me know in the comments if you’ve tried Delta Chat recently. Do you think it's a good bulwark against governments that are tightening their grip on the internet?
  • Recent Achievements

    • One Year In
      bernmeister earned a badge
      One Year In
    • Week One Done
      Scoobystu earned a badge
      Week One Done
    • Week One Done
      tuben earned a badge
      Week One Done
    • First Post
      OffsetAbs earned a badge
      First Post
    • Reacting Well
      OffsetAbs earned a badge
      Reacting Well
  • Popular Contributors

    1. 1
      +primortal
      471
    2. 2
      +Edouard
      217
    3. 3
      PsYcHoKiLLa
      156
    4. 4
      Steven P.
      73
    5. 5
      FloatingFatMan
      71
  • Tell a friend

    Love Neowin? Tell a friend!