How to use Postbox with a large Gmail "All Mail" folder
Due to how Gmail's IMAP gateway works, messages in Gmail can appear in multiple folders in Postbox: once in the "All Mail" folder and once for every label on the message (including labels like "Inbox" and "Sent").
This can result in a large "All Mail" folder (more than 100K messages) and cause performance and memory issues with Postbox.
Two recommended workarounds for this is to limit the number of messages allowed to be downloaded, or to unsubscribe from the Gmail "All Mail" folder.
How to Enable Folder Size Limits
- Log into Gmail.com
- Go to Mail Settings (the "gear" at the top right corner of the website)
- Select the Forwarding and POP/IMAP tab
- Scroll down to the Folder Size Limits section near the bottom, and choose the option to "Limit IMAP folders to contain no more than this many messages".
How to Unsubscribe from the "All Mail" Folder
- Make sure the "All Mail" folder is no longer a "special folder". (i.e., the "All Mail" folder is the default Archive folder for Gmail accounts. It can re-appear if it remains to be the default. To change the Archive destination, please see this Knowledge Base article).
- Right-click (control + click on Mac) the folder, and select Subscribe...
- In the subsequent window, select the "All Mail" folder, usually hidden within the [Gmail] or [Google Mail] folder.
- Click Unsubscribe
After making changes to large folders, you may want to reset (Tools | Indexing | Reset All Folders...) and re-index (Tools | Indexing | Index All Folders...) to increase performance and reduce the amount of memory that Postbox uses.
If you unsubscribe to the "All Mail" folder in Postbox and then archive messages from the Gmail web client (http://www.gmail.com), those messages will not appear in Postbox.