Problem emailing one mail domain

icemoom · ‎09-07-2012

Hi,

Wondering if anyone can help, we are having issues emailing one specific customer with the mail domain mail.rooftech.info. Any email we send to the company is bounced back after 3 days (the period set in our bounce profile), it's giving a SMTP 5.4.7 error bounced by destination server delivery time expired. We can do an nslookup from the Ironport for mail.rooftech.info and their correct mail exchange address appears. Any idea what could be the cause? I've attached the message tracking log.

Excuse my ignorance but I am a novice concerning email security.

We are using AsyncOS 7.1 for IronPort C160 build 017.

Regards,
Ross

Andreas Mueller · ‎09-11-2012

Hi Ross,

the error may be a bit misleading as it is most likely not the remote server giving that error, the system just has detected that the message is older than three days and thus bounces it. I just checked that server, and seems it does not respond to any requests:

telnet mail.rooftech.info 25

Trying 89.213.91.141...

telnet: connect to address 89.213.91.141: Operation timed out

telnet: Unable to connect to remote host

I also checked the MX record for rooftech.info, and that obviously is something different:

;; ANSWER SECTION:

rooftech.info. 14400 IN MX 5 mailscanner.rocc.co.uk.

And that connection just works fine:

telnet mailscanner.rocc.co.uk 25

Trying 135.196.30.100...

Connected to mailscanner.rocc.co.uk.

Escape character is '^]'.

220 mailscanner.rocc.co.uk ESMTP ROCC MailClean

Unfortunately your message tracking has the recipient domain and IPs obscured, so I cannot tell which of the hosts above are you trying to reach.

BTW, there is a handy tool on the CLI that you can use to troubleshoot problems like that

CLI: diagnostic network smtpping

When asked for a domain the one you wanna reach, the command will perform an MX lookup and will ask if it finds such entries. When asked if to send a message, you can answer No, after that the tool will try to connect the remote host and perform some simple checks without actually sending a message.

Hope that helps,

Andreas