Se você usa o Postfix
- adicione "message_size_limit = 102400000" em "/etc/postfix/main.cf"
- recarregar postfix: sudo postfix reload
- verifique message_size_limit
Exemplo (100Mb):
$ sudo postconf message_size_limit
message_size_limit = 102400000
Isso está documentado no site do Postfix :
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.