Technical Tip: FortiMail Maximum Email Message Size limit is configurable

Description

This article describes how to configure the maximum email message size limit.

Scope

FortiMail.

Solution

The maximum email size that the FortiMail can relay is configurable between 1 and 204,800 kilobytes. This option cannot be set to 0 (disabled).

The maximum size of the message is set in Profile -> Session, under SMTP Limits (Cap message size (KB)). Then this session profile needs to be applied to an IP Policy to take effect (double-check if the particular email matches the IP policy with the applied session profile).

There is also a domain setting for the message limit under Domain & Users -> Domain, choose the domain, expand 'Advanced Setting' -> Other, and update 'Maximum message size (KB)'.

In the Content Profile, the message size can be also configured under the scan option. By default, this setting is disabled. 

In the Content profile different actions can be used.

• For outgoing emails, only the size limit in the session profile will be matched. If there is no session profile defined or no IP-based policy matched, the default size limit of 10 MB will be used.
• For incoming emails, the size limits in both the session profile and domain settings will be checked. If there is no session profile defined or no IP-based policy matched, the default size limit of 10 MB will be compared with the size limit in the domain settings. FortiMail will use the smaller size.