Exchange 2007 sending mail problems

[LaraBoft]

Hi all! I have a small problem with my Exchange 2007 server, but I can't find a real solution for it. When users try send email to certain domains they get an error stating: Relaying denied 550 Sender verification error (recipient) for users emailaddress. However, this happens only with a few addresses. 99% of the email is going to the receiver without a problem. This is the situation: PDC (Win2008) , Exchange server (Win2008 & Exchange 2007). Email is sent directly to the internet using DNS on the PDC. Any ideas?

[Cyber Nemesis]

Lots of potential here. Make sure the domain they are sending to is accurate, to often people use .com when it should be .net, etc. Try a simple telnet test to the MX for the receiving domain, this is not full proof as some security will prevent telnet on 25, but a good place to start. Also can you send to this domain(s) from yahoo, gmail, etc. You could be on a RBL. Also see if your ISP has smarthosting capabilities and route these domain(s) through thier smarthost until you get your RBL issue fixed.

Set the event log level to expert for transport\smtpsend, then try to send to the domain(s) in question. This should put additional details in your app log and give you more to go on.

And finally you may in fact contact the admin on the remote side and work with them, this would help ID what RBL you are on, if that is the case.

[LaraBoft]

The strange thing is that it always have worked. I have tried to send an email to the domain, spelled it correct and got the same error. When we try to send from a Mac, the error is: The following organization rejected your message: mail-in3.tiscali.nl. and 550-Previous (cached) callout verification failure 550 Sender verification error (recipient). Very strange. This is a problem that started 3 weeks ago. Before this it has always worked. We are not on a blacklist, I already checked this...

How can I set the log level to expert? This is new for me....

[Cyber Nemesis]

Get-EventLogLevel

and you will see all the event you can modify.

Set-EventLogLevel MSExchangeTransport\SmtpReceive -Level expert

Be sure to change it back once completed testing or you'll spam your app logs.

[Adam20]

What ISP are you using? is it a dynamic IP address you have?

EDIT: If you are using a dynamic IP address most systems block dynamic address from recieving emails at their end, which will be why some work for you and some dont.

In the end I had to relay the emails I sent through my ISP's SMTP server.

Edited April 9, 2009 by Adam20

[Cyber Nemesis]

Can you send to the email from other sources, yahoo, gmail, etc?

I think in the end you will need to call to tiscali.nl and speak with them as you have little control over what they reject. They could be using a new security product as the mail gateway or something odd like that they recently implemented.

[TheReaperMan]

have you checked your email domian on sites like mxtoolbox etc?? to if it blacklisted etc?

[LaraBoft]

Crash.Override: I'll try the eventlog tomorrow when I'm back at work. I tried to send the email from other email domains, no problems there. Something even stranger: when I send the mail using Outlook Express instead of Outlook, it's not a problem. Even if I use the SMTP server from Exchange.

Adam20: I have a static IP address.

I need to say this: incoming mail is handled by an external SPAM filter. This Spamfilter catches all email for our emaildomain and then sends it to my Exchange server. I read somewhere that it can the PTR records are not valid. Can it be this?

Thanks for all your replies!

Edit: I forgot to mention: I checked our emaildomain if it's blacklisted on mxtoolbox already. It's not...