Mail receiving delay

Question

Hi all,
If this has been answered here before, I apologize, I could not find it.
It seems that the mail server is delaying email arbitrarily from outside senders. What is happening is if say "[email protected]" sends an email directly to "[email protected]", the Mac Server is not putting it right through, it will show up in a few hours later. But if the same user, "[email protected]" replies to an email sent from "[email protected]" it comes through right away.
The problem is happening very arbitrarily and with multiple outside domains and senders, so I cannot figure out how to troubleshoot it...
Also on a side note, the logs state that some of the users exist more than once. (i.e dovecot[58]: auth(default): od([email protected], [IP Address] ): user "username" exists more than once ). I don't know if this has something to do with it, I kind of figured it was a Workgroup Manager issue with shortnames.

Answer 1

Chris,
I agree that inexperienced users are overwhelmed and may have difficulties to decide which options they need to use. I also fully agree that greylisting will block significant amounts of spam and is well suited for a mail server maintained by non professionals. However, "stealthy" options confuse new users even more.
In Server Admin, they tick "Enable junk mail filtering" and as soon as they do so, several grayed out options become active. While they may not be familiar to the beginner, the options are written on that page and can be looked up.
Nowhere does it say that greylisting is going to be enabled and so a user doesn't even know what to look for if things do not work. All the user notices are delays.
The problem is further amplified by the fact that the warning logged in mail.log does not specify what is happening. The policy server logs:
"NOQUEUE: reject: RCPT from... 450 ... Recipient address rejected: Service is unavailable;"
while for example Postgrey will log something like:
"NOQUEUE: reject: RCPT from... 450 ... Recipient address rejected: Greylisted, see http://postgrey.schweikert.ch/help/example.com.html;"
Having this extra bit of information would help the inexperienced user in asking for help.
Add to this that greylisting can cause the loss of legit mail if not provided with a whitelist and you get unhappy users.
If it was my call, I'd implement one or more of the following in order of priority:
-A seperate checkbox for Greylisting
-Replace "Refuse all messages from these hosts and networks" with a listbox for whitelisted domains (Refusing mail by IP has become pointless nowadays. Spam comes mostly from botnets).
-Log an explicit warning in mail.log
-If there is no separate checkbox, display a warning when users tick "Enable junk mail filtering", so they now about greylisting
And talking about keeping options down to the minimum: "Accepted languages and locales" is not a very effective measure in fighting spam and can be left to the admins willing to look under the hood.
Thanks for listening.
HTH,
Alex