The email server on my ubuntu machine can only receive mails up to 10 megabytes in size. I would like to change that value, but I'm so blind I can't figure out where to change it.

Could not be delivered because of

Server refused mail at MAIL FROM - 552 5.3.4 Message size exceeds fixed limit

If you use Postfix

  • add "message_size_limit = 102400000" in "/etc/postfix/main.cf"
  • reload postfix: sudo postfix reload
  • check message_size_limit


$ sudo postconf message_size_limit
message_size_limit = 102400000

This is documented on the Postfix site:

message_size_limit (default: 10240000)

The maximal size in bytes of a message, including envelope information.

Note: be careful when making changes. Excessively small values will result in the loss of non-delivery notifications, when a bounce message size exceeds the local or remote MTA's message size limit.

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Open /etc/postfix/main.cf find message_size_limit and change it from 10240000 (10mb) to e.g. 20480000

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postconf -n | grep message_size_limit



sudo postconf -e 'message_size_limit = 31457280'

Get (to see if it worked):

postconf -n | grep message_size_limit

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