Internal users (same domain) unable to send emails to internal users (same domain)

[tvliew]

Hi All,

First, I must say I am new here and I love Zimbra for such a wonderful product.

Okay, back to my problem. Well, I have ZCS 6.0.10 running on CentOS 5 for more than a year without issues. Then only thing that happens once in a blue moon is that some users often are not able to receive emails from one another. That means, userA@example.com sents to userB@example.com, userC@example.com and userD@example.com, they don't get it. The clue is that this email had some attachments. If the user were to resend a test email without any attachments, they get it.

I have scourged through the /var/log/zimbra.log but could not find what is causing the issue. I see 'Passed CLEAN', '250 2.0.0 OK' and 'queued_as:' which tells me that all is okay.

Is there something I may have missed out?

[tvliew]

Dear All,

Sorry again. Also, what happens if the email from the internal users to the other users is delayed? That means userA@example.com sents the email to userB@example.com & the rest, but the other users gets it the next day.

[phoenix]

Originally Posted by tvliew

I have scourged through the /var/log/zimbra.log but could not find what is causing the issue. I see 'Passed CLEAN', '250 2.0.0 OK' and 'queued_as:' which tells me that all is okay.

Posting one line out-of-context does nothing to help diagnose the problem.

Originally Posted by tvliew

Is there something I may have missed out?

That's difficult to say as you've really given no details about your configuration on whether: it's a new install; it's a single or multi-server installation; you've just experienced this problem; it's happened before; you're behind a NAT router (or firewall); you've set-up a Split DNS (you must if you're behind a NAT router); you've tried any of the solutions in the forums (there's plenty of threads on this topic); which solutions you've tried and what were the results.

[tvliew]

Hi Phoenix,

No, this isn't a new install. It has been running for a year plus. And it is definitely a single server installation. And yes, I am behind a NAT firewall and yes, with split DNS (I read about this and has always been there since day one). So, I have nailed that.

My question really is, where should I first look in the logs to trace when a mail came through, and when it goes into the user's mailbox?

[phoenix]

Send an email from one user to another and tail the log file to see what happens to the message. Is it getting deferred? What are the errors? Is there a restriction on the size of attachments? Are the attachments within the limit for your server (what is the limit and what size is the attachments)? Does this only happen for local email or can you send the attachment to an external recipient?