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Postfix Message Size

Here is how to increase your mailbox size in Postfix. Some common e-mail providers allow attachments of up to 25MB, however, the maximum attachment postfix will accept is only 10MB. In order to avoid having some messages blocked with the SMTP error message '552 5.3.4 message size limit exceeded', you can increase the postfix message_size_limit by adding the lines below to your configuration file main.cf in /etc/postfix/. You can set the value to anything you want. I went with 100000000 bytes, which equals 100 megabytes.

message_size_limit = 100000000
mailbox_size_limit = 0 (unlimited)