Error when forwarding emails via mail filter

Symptoms

Forwarding emails using Sieve rules does not work. The mail filter log at the path /var/www/<user_name>/data/email/<domain_name>/<email_box>/.dovecot.sieve.log contains the following error:

resend: line 8: error: number of redirect actions exceeds policy limit (5 > 4).

Causes

The default mail filter forwarding settings are set to low values to avoid unwanted mailings.

Solution

To increase the number of emails forwarded by the mail filter, uncomment and increase the value of two parameters in the configuration file /etc/dovecot/conf.d/90-sieve.conf:

• sieve_max_redirects - number of emails that can be sent at once (4 by default);
• sieve_max_actions - total number of actions at once (23 by default).

If the number of recipients exceeds the value of the sieve_max_actions parameter, both parameters must be changed. Otherwise it is only required to change the value of the sieve_max_redirects parameter.

After changing the parameter values, restart the Dovecot mail server service with the following command:

systemctl restart dovecot