I’ve experienced this as well a few times recently but haven’t had the chance to debug it at all.
This configuration must be done in your text editor, not in aerc.
For example, you could configure vim’s settings for filetype=mail.
for maildir it will be the path separator of the OS ("/" in all supported OSes)
Actually, maybe this should be configurable for maildir. In the maildir++ format, '.' is used as the separator.
Though perhaps it makes more sense to configure it in accounts.conf by pointing to maildir++:// or something and then inferring the separator from that?
In any case, we don't have great support for maildir++ yet so maybe we don't need to worry about it now.
We're going to need more information here. In general, this should work correctly. Can you share a complete message (including headers) which reproduces this?
Just to confirm, are you seeing this in the msgviewer?
I don't have this problem on the msglist, but I have since noticed this problem on the msgviewer. I think it's to do with the complex invalidation logic for that component, but want to be sure we're talking about the same thing before digging in.
This is fixed in 4ab82bf306370ae4d79c12f5028a51b38fe40547 -- aerc will now display an error for that specific message rather than panicking. You will still need to fix whatever is improperly naming your maildir file(s).
This can be closed, invalid.