Moving a message to another mailbox (or Gmail's Trash) generates a second duplicate copy of the message in All Mail

Dave's Recommended Settings for Best Gmail-Outlook (2011) Compatibility

Gmail:

Go to Gmail on the web.

Under Settings > Forwarding and POP/IMAP > IMAP Access:

• Status: Enable IMAP
• When I mark a message in IMAP as deleted: Auto-Expunge off - Wait for the client to update the server.
• **When a message is marked as deleted and expunged from the last visible IMAP folder:**Move the message to the Bin
• Folder Size Limits: Do not limit the number of messages in an IMAP folder (default)
• I aso recommend that you disable****POP Download, as allowing a default configured POP email client to access your Gmail account could result in loss of messages form your IMAP client.
• Save Changes.

Under Settings > Labels:

Uncheck Show in IMAP for the following labels:

• Starred
• Important
• Chats
• All Mail

Outlook 2011:

Under Outlook Preferences > Accounts > (your Gmail account) > Advanced > Folders:

• Store sent messages in this folder: Choose (your Gmail account) > [Gmail] > Sent Mail
• OK and close Outlook Preferences completely. I will explain the reason for this seemingly odd step later. *
• Re-enter Outlook Preferences > Accounts > (your Gmail account) > Advanced > Folders and continue settings as below:
• Don't store a copy of sent messages (but the greyed out drop-down must still show "Sent Mail (Server)"
• Store draft messages in this folder: Choose (your Gmail account) > [Gmail] > Drafts
• Store junk messages in this folder: Choose (your Gmail account) > [Gmail] > Spam
• Move deleted messages to this folder: Choose (your Gmail account) > [Gmail] > Trash (or Bin if your local language settings show as this)
• When Outlook closes, permanently erase deleted messages: Never. (The result of this setting is that Gmail will automatically delete messages after 30 days anyway. If you prefer, you could set a shorter interval here.)
• OK and close Outlook Preferences completely.

Under Tools > Junk E-mail Protection... > Level:

• None: Turn junk e-mail protection off. (This allows Gmail's very good Spam protection to manage your junk e-mail. Providing you have also made the settings in the section above, you can use the Junk ribbon item in the Home tab to send or remove messages to or from Gmail's Spam folder. However, it will have the side effect of disabling junk protection for any other accounts you may have configured in Outlook.)
• OK

* Why the seemingly odd step of setting and then unsetting the "**copy of sent messages"**setting?****If you do not do this, and you have Outlook Preferences > General > Folder List > Group similar folders... checked, the Sent Items > (your Gmail account) in the Navigation Pane will appear empty and you will not see your Sent Mail in this folder.

With these settings, Outlook 2011 14.2.2 will play well with Gmail IMAP.

Dave.

I have done further research on this problem and have come up with a workaround. This involves changing a setting in Gmail's IMAP configuration.

The Workaround:

Go to Gmail on the web. Under Settings > Forwarding and POP/IMAP > IMAP Access.

• Change "When I mark a message in IMAP as deleted:" to "Auto-Expunge off - Wait for the client to update the server."
• Change "When a message is marked as deleted and expunged from the last visible IMAP folder:" to "Move the message to the Bin"
• Save Changes.

The effect of this change is that:

• Deleting a message in Outlook 2011 14.2.2 will move the message to Gmail's Trash folder.
• Moving a message in Outlook 2011 14.2.2 will move the message to the selected target folder.
• Either of the operations above will generate a spurious duplicate of the message, but that spurious duplicate will be filed in Gmail's Trash and eventually be deleted after 30 days. Without this change, the spurious copy is filed in "All Mail" and stays there forever (wasting quota and also a security issue for apparently deleted emails).

In order to check whether this Gmail setting change caused any adverse effects with other IMAP clients, I tested the Delete and Move behaviour (after the Gmail setting change) on the following clients:

• Entourage Mac 2004
• Entourage Mac 2008
• Outlook Windows 2010
• IOS (iPad) Mail

In all cases, these mail clients continued to function correctly for Delete and Move operations and did not generate spurious duplicates.

I concluded that this workaround gives the best results with Outlook 2011 14.2.2 without adversely affecting the other IMAP mail clients I tested.

In a separate post, I will enumerate in full the settings (both Gmail and Outlook 2011) that I have found give maximum compatibility between Gmail & Outlook 2011.

Dave

Once I found out that I had to remove Outlook (client) rules and rely on Gmail filters to do the rules behind the scenes (on the server), then duplicates stopped.  Thanks Dave and Scott!