How do I remove maximum limit size for email?

I have successfully set up an email server using this tutorial: *How To Configure a Mail Server Using Postfix, Dovecot, MySQL*, and SpamAssasin but there appears to be some sort of limit to the size of email attachments I can send or receive. It means I have to resize photographs before sending them and my correspondents cannot understand why they cannot send me pictures either. I need this communication for my work.

Can anybody please tell me where to find where such limits are set among the huge plethora of configuration files in this set up? I have been steadily ploughing through them but it is taking far too long and there are still far to many left to plough through.

I believe it is the server, not the client. But just in case it helps, the client is Thunderbird.


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To change the maximum limit you need to edit /etc/postfix/

Search for message_size_limit using :

nano /etc/postfix/

Use Google to calculate Bytes to GB (1GB in Bytes) for e.g. 1GB are 1000000000 Bytes

now change message_size_limit to e.g. message_size_limit = 1000000000 if you want 1GB

PS: Show some love if it works by clicking the hearth

Thanks Eldin. That’s done the trick. Sorry, I misread your response at first pass. The message size limit line was indeed missing.

That line currently reads “mailbox_size_limit = 0” which, if I understand it correctly, means unlimited in postfix. That’s how I want it. I don’t want a limit set anywhere else either. However, I believe that line refers to the total amount of all the emails, aggregated together, which can be held within a mailbox, not to the maximum size of any one email including attachments.

As it stands I cannot send more than a couple of photos under 1MB and none over 1MB. Which actually confirms the line quoted does not mean zero size of either the mailbox or of the individual messages therein.

I have no wish to change the limit to any particular size. I want to remove it altogether so the arithmetic, which I understand perfectly well already thanks, is irrelevant. But where, if not in /etc/postfix/, is a limit being imposed?