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

Search for message_size_limit using :

nano /etc/postfix/main.cf

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

That line currently reads “mailboxsizelimit = 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/main.cf, is a limit being imposed?

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