e-mail not sending / reviece @ random

[rszkutak]

ok tekkies, here is a brain stumper to thump on you all.

I am having some issues with my DA server. It is based on RH 7.x, using all the normal goodies with redhat.

I am having a very ELUSIVE problem. I have noticed this issue myself and frankly thought it was just my issue and not with any of my customers until one brought it up to me. I asked a few other good clients as well, and they too experience it from time to time.

The problem is this:

At totally random times, days, etc... somehow the e-mail system stops sending mail through it's SMTP for a few minutes to a few hours. The exact time is unknown because this is all totally at random.

Sometimes this issue is amplified by my users on the server, not being able to send mail back and forth to each other for minutes or hours. The e-mails do send, and do not bounce back... they just vanish into cyberspace. The clients are using MY SMTP service and not their ISP, so i know that is not the possible issue there.

Likewise I can duplicate this problem, again it is all at random. Sometimes this problem doens't appear to show itself for days, then all of a sudden WHAM, it's back!

For the life of me, I cannot even begin to think what it might be or where to possibly look.

I am also having some issues with Squirrelmail on one domain. For some reason "some" new users cannot log into teh squirrelmail system. By definition of "some" I mean, if i create say 25 users right now, about HALF would not be able to log into squirrelmail, the other half would. However all users can log into UBI, but UBI locks them out from the ability to do anything once thier account reach's 5mb, eventhough the CP shows them at "unlimited - 0" size.

I don't think these issue are really related, but they could be... ?

Does anyone have any good idea's of what this might be, or where to look - start looking?


thanks,
-Rob

 

[nobaloney]

I am having some issues with my DA server. It is based on RH 7.x, using all the normal goodies with redhat.

That was a very good choice at one time; I hope you're keeping it up to date.

At totally random times, days, etc... somehow the e-mail system stops sending mail through it's SMTP for a few minutes to a few hours. The exact time is unknown because this is all totally at random.

Which version of the exim.conf file are you using. If you post the first ten or so lines of your exim.conf file, that would be a good response to this question. Earliest versions of the exim.conf file allowed all email on to the server; even email to nonexistent addresses.

That causes a backlog in the outgoing queue, as exim tries to send back tons of spam to forged senders. And that can cause exim to slow or even appear to stop completely. If so, updating to the newest exim.conf file can help (but be sure to add the files required under /etc/virtual, as documented in the file).

Sometimes this issue is amplified by my users on the server, not being able to send mail back and forth to each other for minutes or hours. The e-mails do send, and do not bounce back... they just vanish into cyberspace.

Once emails are accepted for delivery they can't just vanish. At least not without a trace in the logs. If the emails "send" as you put it, then they've either been accepted by your server, or by their ISPs server, and barring a catestrophic server failure or intentional discard, they're somewhere, awaiting delivery.

The clients are using MY SMTP service and not their ISP, so i know that is not the possible issue there.

You can say this, but you can't prove it and it may not be true, on a case-by-case basis.

Why?

Because many ISPs block port 25 off their network completely so you can only use their servers, and many who do not, silently redirect all port 25 traffic to their own mailservers no matter what mailserver you set in your email client for delivery.

The only way to tell is to examine the headers on a sent email. What you're looking for is the lowest "Received:" line (the one closest to the body of the email); it should have your server name and/or IP# in it. If it doesn't, the mail isn't going out through your server.

If you're having a problem understanding what I mean, then send me an email, from your desktop, using your server as the outgoing email server in your mail client settings, and in the email tell me (among the usual niceities) your server's main IP#. I'll send you back an analysis of your headers, and show you what to look for.

Likewise I can duplicate this problem, again it is all at random. Sometimes this problem doens't appear to show itself for days, then all of a sudden WHAM, it's back!

This sounds like a problem with the mail server getting too busy, perhaps because it's inundated with undeliverable email in it's outbound queue.

For the life of me, I cannot even begin to think what it might be or where to possibly look.

Start by tailing your /var/log/exim/mainlog file while sending an email, and see what entries, if any, appear in the logs while you're sending the email.

I am also having some issues with Squirrelmail on one domain. For some reason "some" new users cannot log into teh squirrelmail system. By definition of "some" I mean, if i create say 25 users right now, about HALF would not be able to log into squirrelmail, the other half would.

While that's probably not the same problem, it points to a possible problem with DNS resolution on the server. What's the contents of your /etc/resolv.conf file? What happens when you try a squirrelmail login? Do you get an error message? Or does your browser lock up?

However all users can log into UBI, but UBI locks them out from the ability to do anything once thier account reach's 5mb, eventhough the CP shows them at "unlimited - 0" size.

That's a separate quota en UebiMiau; search for UebiMiau in these forums and you'll find more information.

Jeff