Mail stuck in Outbox for a long time before they are sent. Very slow mail acceptance by server
- When the users send mail using a desktop email client like Outlook, Thunderbird etc, the mail seem to be stuck in the Outbox for a very long time before being accepted by the mail server.
- This leads to slow delivery of mail
- In some cases it is leading to duplicate mail delivery to the recipients.
- SMTP concurrency as observed from the /var/log/messages file was high indicating that the SMTP processes were taking very long to finish their work
- SMTP concurrency for the 127.0.0.1 IP was also high, indicating that Baya users are also facing problems.
- To troubleshoot why the SMTP processes are taking so long to complete, you can look at the prequeue log, which provides a breakdown of the time taken to process each stage before it is queued.
- In this case we found that the SPAM stage is taking the longest.
- SPAM processing depends on heavily on the DNS to function properly and respond quickly.
- In this case the DNS was functioning poorly.
Fix the DNS performance issue
Tune the SPAM engine to turn off certain tests which depend on DNS
Turn off Network test
vi /mithi/mcs/components/mithi-as-spamassassin/conf/server/spamd.options.conf.sh Change line SPAMDOPTIONS="-x -d -u spamc" to SPAMDOPTIONS="-L -x -d -u spamc"
Turn off RBL checks
vi /mithi/mcs/modules/mithi-bl/conf/server/antispam.conf.sh Change SKIP_RBL_CHECKS=0 to SKIP_RBL_CHECKS=1 and DNS_AVAILABLE=yes to DNS_AVAILABLE=no
Regenerate the configuration
Restart the spamassassin service