- sending a test mail with SWAKS returns DUNNO (swaks is an SMTP test tool)
the difference appears to be the "size=0" line that Postfix sends if I use SWAKS.
The postfix policy server sends over a bunch of key=values when it runs. It has no idea why its running, it doesn't know you want it to be checking for over quota. It just sends every thing over to dovcot who knows that you want to be checking for over quota. One of the key=values postfix sends is size=<bytes> of the message size. Dovecot looks at this and ignores the rest of what postfix sent and returns a result.
Now im guessing, maybe because you are using a testing tool, maybe it is not sending a message body in the email transmission, so postfix is correcting reporting that message has an email body of zero bytes (size=0). Dovecot must approve this because current maildir size + 0 != over limit. Maybe you are setup correctly and its just the testing tool that creates an edge case you wont experience in the wild.
Like you said when sending a real email it gets rejected right?