Ubuntu/Debian & Postfix: Increase attachment size limit

By default postfix limits the attachment size to about 10 MB. You can determine the current limit with the following command:

# sudo postconf | grep message_size_limit
message_size_limit = 10240000

To increase the limit add (or change) the following setting in the file /etc/postfix/main.cf:

# 20MB
message_size_limit = 20480000

After restarting the postfix service the new limit will be active:

# sudo service postfix restart