Skip to content

Max. message size (attachment size)

Open data/conf/postfix/extra.cf and set the message_size_limit accordingly in bytes. See main.cf for the default value.

You will also need to adjust message size in Rspamd and Clamav configurations:

  • in data/conf/rspamd/local.d/options.inc add max_message parameter, check Rspamd Docs for defaults
  • in data/conf/rspamd/local.d/external_services.conf adjust max_size parameter for oletools
  • in data/conf/rspamd/local.d/antivirus.conf adjust max_size parameter for clamav
  • in data/conf/clamav/clamd.conf adjust MaxScanSize and MaxFileSize
  • in mailcow.conf set NGINX_MAX_BODY_SIZE above the new message size (default 128m), it limits requests to SOGo webmail, CalDAV/CardDAV and ActiveSync. Apply it with docker compose up -d.

Restart Postfix, Rspamd and Clamav:

docker compose restart postfix-mailcow rspamd-mailcow clamd-mailcow

docker-compose restart postfix-mailcow rspamd-mailcow clamd-mailcow

Request size limits in nginx

nginx limits the size of requests:

  • SOGo webmail, ActiveSync and CalDAV/CardDAV: NGINX_MAX_BODY_SIZE in mailcow.conf, default 128m. The value uses nginx syntax (e.g. 128m or 1g), 0 means unlimited, an invalid value falls back to 128m. Keep it above message_size_limit, otherwise large mails cannot be sent through SOGo or ActiveSync (error 413).
  • mailcow UI, API, Rspamd UI and own locations in site.*.custom: 64 MB. For larger uploads in own locations, set client_max_body_size there (see Config expansion in mailcows Nginx).