Limits – Max Message Size

The Max message size limit is a special case worth mentioning, as it can be set as a Global limit as well as a Domain user limit and a User limit.

If the Global limit is checked and set in Mail Service - SMTP - Limits and Override Global limits is not checked then the limit set will be applied to all messages from all users in all domains on this server. Any message larger than the size set will be rejected.

If Override global limits is checked then the limits are checked in the following order until a non-zero value is found (if only zero values are found then the message is passed).

1. User limit
2. Domain User limit
3. Mail SMTP limit

Example 1:

1. Mail Service - SMTP - Limits has Max message size checked and set to 10MB
2. Override Global limits is not checked

Any message with a size greater than 10MB will be rejected.

Example 2:

1. Mail Service - SMTP - Limits has Max message size checked and set to 10MB
2. Override Global limits is checked
3. Use Domain limits is checked
4. Use User limits is checked
5. DomainA has the Domain user limit of Max message size set to 20MB
6. UserA has the User limit of Max message size set to 50MB
7. DomainB has the Domain user limit of Max message size set to zero
8. UserB (in DomainB) has a User limit of Max message size set to zero.

If UserA tries to send a message of size 40MB it will be accepted as his User limit (f) takes priority

If any other user in DomainA tries to send a message of size 40MB it will be rejected as it breaks the Domain limit (e) of 20MB

If UserB tries to send a message of size 40MB it will fail as it breaks the Mail Service Limit (a)