Having seen the recent thread with Kostya's explanation of exclusivity of undo vs. deletion confirmation,
http://www.aqua-mail.com/forum/index.php?topic=4759.msg27421#msg27421 , I thought that there should be a graveyard of deleted messages.
Yes. There should be an option: once a message is deleted, it is uploaded to some cloud-based storage.
So, the full set of options for the deleted messages (and the corresponding chain of events) should be like this (all could be enabled at the same time):
Deletion Confirmation - enabled
Undo - enabled
Deleted messages moved to "Deleted"
Messages deleted from "Deleted" go to the graveyard.
Confirmation for that - enabled.
Undo for that - enabled (similar to the newly added one)
... and then a "restore from the dead" operation, - to bring the message from the graveyard.(*)
What I am not sure yet, if that latter operation should have an "undo" associated with it. Sort of "undo all this horror!".

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(*) That could be a separate paid service with a paid app, monthly fee, and/or per-use fee !
