Mailing lists are not accessible on a Plesk server: 403 Forbidden

Applicable to:

• Plesk for Linux

Symptoms

• Unable to open Mailman welcome link for subscriber like http://lists.example.com/mailman/options/list/jdoe%40example.com:

  CONFIG_TEXT: 403 Forbidden

• Error like the following can be found in /var/log/httpd/error.log (CentOS/RHEL-based OS) or /var/log/apache2/error.log (Debian/Ubuntu-based OS):

  CONFIG_TEXT: [:error] ModSecurity: Access denied with code 403 (phase 2). Matched phrase ".com/" at TX:extension. [file "/etc/httpd/conf/modsecurity.d/rules/comodo_free/10_HTTP_HTTP.conf"] [line "27"] [id "210730"] [rev "3"] [msg "COMODO WAF: URL file extension is restricted by policy||example.com|F|2"] [data ".com"] [severity "CRITICAL"] [tag "CWAF"] [tag "HTTP"] [hostname "lists.example.com"] [uri "mailman/options/list/jdoe%40example.com"] [unique_id "Xg7MRz0uIXKxE1qyA5HQ7gAAAIE"]

Cause

Web Application Firewall (ModSecurity) is blocking access.

Resolution

1. Log into Plesk.
2. Go to Plesk > Tools & Settings > Web Application Firewall (ModSecurity).
3. Specify the rule ID taken from the log ([id "210730"] in the example above) in Switch off security rules section.