Technical Tip: Allowed message size for Inbound/Outbound mails

[kagritelis]

Description	This article describes how to Resolve Issues related to emails that are NOT Received/Sent due to Size Limits.
Scope	FortiMail.
Solution	The Default FortiMail Maximum Message Size is 10 MB. Max Content Limit: Detected by Content Profile. Message size (43385KB) exceeds the maximum size (35950KB). Additionally, an extra log entry will appear when the message exceeds the configured size limit. Milter: data, reject=554 5.7.1 Message refused by Attachment check. This email from 172.26.61.4 has been rejected. The email message contains banned attachments. Max Session SMTP Limit Options: message size (38459532 Bytes) exceeds maximum (10485760 Bytes) 552 5.2.3 Message size is over limit (10485760) These 2 Options Need to be Changed According to the needs. This can be done by following the Steps Below: Content Limit. Go to Policy -> Recipient Policy -> < Inbound/Outbound (choose the Preferred Policy) -> Content Profile -> Scan Options -> Maximum size (arrange it according to the needs). SMTP Limit: Go to Profile -> Session (choose the Preferred Inbound or Outbound Session Profile) -> SMTP Limits -> Cap message size (KB) at: (arrange it according to the needs). Note: For incoming/outgoing email, the size limit in the session profile and content profile will be checked. Outbound Emails: If in the preferred IP Policy there is no Session Profile, or if no IP policy matched, the default size limit of 10 MB will be used. Inbound Emails: If in the preferred IP Policy there is no Session Profile, or if no IP policy matched, the default size limit of 10 MB will be compared with the size limit of the respective domain specified in the domain settings. FortiMail will use the smaller size. Inbound email IP policy should look like: Source:0.0.0.0/0  as they are coming from the internet. Destination: FortiMail interface IP (can find this IP from cross-search logs indicated as Destination IP). In case of HA(A-P), need to use Cluster/VIP IP as the Destination. Session Profile: With the new size configured. If a session profile is matched,  FortiMail will use the smaller size between the session profile and the content profile.