DSN: Service unavailable with incoming emails.

[#1]

Hello, We are having a problem with incoming e-mails. The FortiMail units are configured for HA with MR4 Patch 5. and reside in the DMZ of a FortiGate 310B HA cluster. The SMTP server for that domain is a Microsoft Exchange 2003 server with in the internal zone of the FortiGate cluster. The problem is that when emails are received for users in the specified domain we get the following message in the log: 8 2009-07-22 12:35:50 smtp n6MGZomd014345: DSN: Service unavailable event information 9 2009-07-22 12:35:50 smtp to=<jose.rios@packersprovision.com>, delay=00:00:03, xdelay=00:00:00, mailer=esmtp, pri=39930, relay=packersprovision.com. [172.16.88.54], dsn=5.0.0, stat=Service unavailable This behavior is random, meaning some emails get to the users but some don' t. Thanks in advance for your help.

[Carl_Wallmark]

Hi, I have seen this a number of times, and for me, it was when the FortiMail wants to start using TLS sessions against the exchange server, and if it´s not setup properly it will not work. Go through your settings on the exchange server/fortimail and disable all TLS.

[#3]

Hello, Thank you for your quick reply. I have checked both the FortiMail and the Exchange and none of them is using TLS. The FortiMail reply to the email sender contains the following transcript, even though the destination addresses are valid. >>> HELO FortiMail-100. <<< 501 5.5.4 Invalid Address 554 5.0.0 Service unavailable

[Carl_Wallmark]

What happens if you change your HELO command to, let´s say " HELO fortimail.yourdomain.com" ??

[#5]

OK found the cause of the problem. I was missing the Local domain from the local host settings. Thanks for your help.