I posted this to the Gmail support forum, but I suspect that it needs expertise under the GUI hood.
I use the desktop installation of Outlook 2019 to connect to my gmail account with IMAP. All messages in my Inbox are also in my "All Mail" folder. This is because any folder (including Inbox) is just a labeling of selected threads in "All Mail". If a message has multiple labels, then it will appear in multiple Outlook folders (the ones to which the account is subscribed).
When I drag a message from Inbox to (say) a folder in another account, it disappears from Inbox but stays in "All Mail". Gmail simply removes the Inbox label from the message in "All Mail". It makes sense.
If I drag a message from "All Mail", again into (say) a folder in another account, then it should either
- disappear from all folders for which it has a label or
- remain in all folders for which it has a label
It would not make sense for the message to disappear from "All Mail" but remain in the other folders. This is because messages in other folders (say) "x", "y", and "z"are simply messages in "All Mail" with tags "x", "y", and "z".
I am seeing exactly the behavior that I shouldn't. In Outlook, if I drag a message away from "All Mail" into a folder of another account, it disappears from "All Mail" but remains in Inbox. This should be impossible, as message that is not in "All Mail" is unavailable for tagging with "Inbox". In fact, the webmail interface shows the message still in "All Mail" and tagged with "Inbox", which makes more sense. Hence, the IMAP synchronization is failing to yield an accurate Outlook folder view of Gmail's message tagging.
This asynchronicity is not fixed by Initiating a folder or server update/sync. Nor is it fixed by unsubscribing from the two asynchronous folders (Inbox and "All Mail") and resubscribing.
How do I get the IMAP client to build a correct view of the messages?
How do I prevent this kind of inconsistency?
Prevention is important because I intend to do a wholesale housecleaning of my email, separating my work and personal messages into different accounts. I have to triage the messages one-by-one. I was hoping that by dragging messages away from "All Mail", these messages would disappear from other folders. This triaging on the basis of individual messages would be impractical if I have to do even the smallest amount of re-synchronization each time.
Actually, it would be even better if a message disappeared from all folders, including "All Mail", regardless of which folder it was dragged out of. I have a feeling that this is asking too much, but to me, that would be the holy grail.