Improve error reporting

[cketti]

Goals:

• report errors to the user with instructions on how to further investigate and/or resolve them
• show some kind of indicator for transient errors, e.g. no network connectivity
• record instances of failing protocol commands, e.g. message X couldn't be moved to folder Y (we also have to undo the local move operation)
• should include a separate UI, i.e. get rid of the "K9mail-errors" folder
• IMAP: if the server closes the connection, but sends an untagged BYE response, display the message to the user

Related: #893

[sedrubal]

👍

This error reporting should also display the long version to this notifications, because there is currently no way to read the complete text:

[KopiasCsaba]

Related: #1362

[deragon]

Sound like this issue asks for a lot of architecture change to make error reporting great. I do agree with this, but that might take some development efforts. In the meantime, I would like to have simple error reporting. For instance, when I reload the messages by dragging down the message list in the Inbox, if a connection error occurred, no message is shown! Should I open another ticket just to get basic error reporting showing up?

[alexanderadam]

Okay, as issue 2480 was just labeled as duplicate, I just want to clearify here, that I would make sense to have no error message at all (no notice, no red blinking led) when the client is offline and the user wants to send a message as I explained it in the issue.

[ccpp]

Please implement this, especially #2480 (i.e., unusable / unnecessary notification in offline mode)