Mark Sapiro wrote:
Mailman's lmtp runner which implements the server that receives mail via LMTP uses the aiosmtpd.lmtp.LMTP class to implement the server. This has a default size limit of 33554432 bytes (32 MB) and that's where the "552 Error: Too much mail data" comes from.
Ah - fantastic! I had tried a fairly crude trawl through the mailman-core container files (not knowing what exactly to look for really), but failed to come up with anything.
There is also the message_size_limit setting in postfix. Presumably you've changed that because it defaults to 10240000 bytes (about 10 MB).
Yes I fortunately did remember to set this to a very high value (way higher than 32MB) during testing.
Thanks so much for the explanation Mark, very much appreciated. Stephen