Applicable to:
- Plesk for Linux
Symptoms
- Cannot send email:
CONFIG_TEXT: Too many concurrent SMTP connections; please try again later
- Postfix is used as mail server. It can be found in Tools & Settings > Services Management.
Cause
Remote mail servers restrict SMTP connections due to exceeded concurrent connections count limit.
Resolution
- Login to Plesk via SSH
- Back up Plesk configuration:
# cp /etc/postfix/main.cf /etc/postfix main.cf.bak
- Add the following parameter to
/etc/postfix/main.cf
:# PARALLEL DELIVERY TO THE SAME DESTINATION
smtp_destination_concurrency_limit = 20 - Reload Postfix:
# service postfix reload
- Try to send emails to reproduce the issue. If it still appears, reduce the
smtp_destination_concurrency_limit
value. If it does not appear, increase the value in order to minimize affecting mail server performance.
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