A message-size filter limits large incoming messages according to the selected rule. It is separate from mailbox storage quota and from server-wide attachment or message-size limits.
IN THIS ARTICLE
Check access and requirements
Decide the largest legitimate message your users need to receive and confirm the rule scope. Email encoding increases the transmitted size of attachments, so a file size on disk may be smaller than the complete email message.
01 Set an incoming email size filter in DirectAdmin
- Open E-mail Manager > SPAM Filters and choose the Size match type.
- Read the units displayed by your form, such as KB or MB, and enter the intended threshold. Do not copy a raw number from a screen that uses a different unit.
- Review what happens to messages above the limit. Where possible, choose handling that allows you to investigate a mistaken threshold instead of silently discarding important material.
- Save the rule and tell affected users which approved file-sharing method to use for larger documents.
- Test with controlled messages below and above the intended threshold, including an attachment that reflects normal business use. Keep tests within provider acceptable-use and message-size policies.
How do I verify the incoming message-size filter?
Confirm the observed behavior matches the configured limit and does not block ordinary correspondence unexpectedly. Check both delivery responses and any spam destination used by the filter.
Resolve setup problems
If a message is rejected even after raising this filter threshold, a server-wide limit may still apply. If the mailbox is full, changing the size filter will not free storage. Remove or adjust only the relevant rule and ask support to identify the actual limit from the bounce text rather than repeatedly increasing values.