I just signed up with a VPS provider (I don't want to mention their name -- as it could be taken as bashing them, which I'm not -- I'm simply finding out if this is a known issue or not.) Anyhow, being new to their service, I've been using e-mail quite heavily. I've noticed that there's a noticable delay in e-mail sending and receiving. When I send a message, it will take a good 8-10 minutes for it to arrive to its destination (as opposed to the less than 30 seconds with my previous host.) Also, when someone sends me an e-mail, same thing, 10 minute window.
The VPS provider is telling me it's a problem with Plesk and they're going to have to open a ticket as they've been seeing it on their servers as of late. Does this sound right? I've been with quite a few Plesk hosts and never seen this.
I don't believe that you have the correct fix for this problem. That would only cause a delay of about 15-30 seconds rather than a long delay. The problem I think you are experiencing is with /usr/bin/qmail_check cronjob. If you edit /etc/crontab and remove this cronjob, then restart qmail, you will find that this problem disappears.
The problem is the buggy qmail_check is written to check if there's messages in the queue every 10 minutes and to start qmail only if there is. The idea is that this saves resources on VE's, but in practice due to the script being buggy it often sends the same emails every 10 minutes, and obviously it always results in an upto 10 minute delay. It's not planned to be part of future Plesk application templates (from 7.5.4 onwards). It occurs only on VPS's because it's not part of the main Plesk distribution, only the application templated version designed for Virtuozzo.
Originally posted by TomK Andrew is correct, it is a Plesk 7.5.3 VPS issue (7.5.2 doesn't have this, and I'm told 7.5.4 won't either)
I thought this too but when I checked it is in 7.5.2. It must have been missing from an earlier version of the 7.5.2 templates then added later, so it may affect some 7.5.2 VE's if the provider isn't using the latest release. I confirmed with VZ support manager a couple months ago it's not included in 7.5.4.