Duplicate GMail in Outlook

It is a problem with how Outlook works with Gmail accounts.

In Gmail, all of a user's email is stored in a single folder named "All Mail". Labels can be assigned by the user to sort mail into what looks like folders. These folders operate much like the 'Smart folder' concept in Outlook, i.e. they are a filter. So while you can see messages in what looks like an inbox folder or some other sub-folder, the message actually resides in the 'All Mail' folder and the label provides a means of seeing the message in the place you designate.

Outlook 2016 for Mac is a traditional mail client that uses folders. When used with a Gmail account, it creates folders for each label found in the Gmail account. Prior to Outlook version 15.21.1, by default the 'All Mail' folder was not automatically subscribed in the IMAP folder list window (Tools --> IMAP Folders) because to do so would mean that Outlook would download all messages twice and store them in two locations (once in 'All Mail' and once in the folder corresponding to the Gmail label).

When the Archive feature was introduced in Outlook version 15.21.1, Outlook's behaviour was changed so that the 'All Mail' folder in IMAP was auto-subscribed and the user was prevented from unsubscribing from it. This resulted in the following adverse effects:

The entire 'All Mail' folder was downloaded. For a large account this is time consuming and for every email Outlook finds that has a calendar appointment it causes the calendar alert to fire. The user's mail store is now double the size it used to be. When the user searches for mail within Outlook, the search engine finds two copies of every email (one in the folder it has been assigned to and one in the 'All Mail' folder. When a user displays the conversation view in email, Outlook displays every message twice because it can find the conversation in both the current folder and the 'All Mail' folder. When a user flags an email for follow up, Outlook displays it as a task in the Task module. Because every email message is duplicated, the task list displays the task (email) twice so the list is duplicated.

The ideal solution would be to permit the user to unsubscribe from the All Mail folder.

An alternative would be to change how the various features that have been impacted work, e.g. search, conversation view, tasks could be changed so that they do not scan the 'All Mail' folder.

The new Gmail account configuration in Insider Fast builds has addressed this partially, e.g. the Sent folder in Outlook no longer displays every message twice. However Conversation view is still impacted.