Attachment indicator missing

[ChristophWurst]

Expected behavior

Envelopes should show if the message has attachments.

Actual behavior

As of #2064 the icon vanished. This is because our hasAttachments flag is custom and not part of the MIME headers. To determine if a message has attachments, we actually have to fetch the full body structure and go through all parts until we've found an attachment. This operation is expensive in two ways. First, we have to fetch a lot more data from IMAP. Headers and body can take some time to transfer for a large mailbox. Second, it requires this iteration for each message. It's therefore O(n*m).

Mail app

Mail app version:

One that has #2064

---

@jancborchardt, before you complain I want to tell you that I already have a strategy in mind about how we can fix this :)

Ideally we can combine this with #2579, where we have to fetch the body structure as well.

[ChristophWurst]

Temporary work on hacking the custom flag into the message cache until I realized the performance penalty: patch.txt