User randomly does not receive E-Mails from users in same domain

[IT_Architect]

I have a random situation that only occurs with one domain.
1. A user does not receive E-Mails from another users from the same domain, but others he will.
2. The user will have no problem communicating with domains outside of their domain, and others in the same domain.
3. The next day, one user will ask the other why they didn't respond. It turns out they didn't get any of the E-Mails they sent. They resend the same message and they get it. If you look in the mailbox through web mail, you can see that the messages from the day before never made it into their inbox, and they never show up later either.
4. When they have the problem, they E-Mail me, on my domain, and we can shoot E-Mails back and forth, no problem.
5. They do not have a dedicated IP, and use the same mail server as many other domains on the same server that have no problems.
6. As a DirectAdmin user, they have 4 other domains, and no problems that anyone noticed with them. They have a normal domain name with no dashes or anything else in the name. It was the first domain set up for the user.
7. There is no E-Mail filtering done ahead at an outside service.
8. SpamAssassin is set to trash spam, but all of their domains are whitelisted in SpamAssassin.

If anyone else has ever experienced this and found a solution, let me know what you determined.

Thanks!

 

[nobaloney]

You'll need to trace specific emails through the logs. When you know of a specific email with the problem, search for it in the logs.

Jeff

 

[IT_Architect]

You'll need to trace specific emails through the logs. When you know of a specific email with the problem, search for it in the logs. Jeff

That sounds like something I can use. What can I search with, the subject line maybe?

Thanks!

 

[nobaloney]

You should be able to search /var/log/exim/mainlog for a subject line; I do that often, creating a test email with a subject that's not likely to appear in the real world.

Jeff

 

[IT_Architect]

You should be able to search /var/log/exim/mainlog for a subject line; I do that often, creating a test email with a subject that's not likely to appear in the real world. Jeff

I've never done that before. I'll try it. Thanks!

 

[zEitEr]

You might want to try with "exigrep", as it allows to put all lines related to one email together, e.g.

exigrep "any search request here" /var/log/exim/mainlog