IMAP4rev1 is fully and almost [1] correctly implemented.
There are some useful protocol extensions supported but some other important ones are missing (e.g. CONDSTORE).
There are no known issues with popular clients but performance may be a bit rough. Both due to missing extensions and storage implementation quality e.g. SEARCH may get slow for large inboxes.
There are no known issues with popular clients but performance may be a bit rough. Both due to missing extensions and storage implementation quality e.g. SEARCH may get slow for large inboxes.
[1] https://github.com/foxcpp/maddy/issues/188