Configure mbsync to Sync Specific IMAP Folders

Prerequisites

1. A working ~/.mbsyncrc with at least one Channel that syncs successfully.

2. If you are new to mbsync, complete Setting Up Offline Email with mbsync first.

Include and Exclude Folders with Patterns

1. Edit the Patterns line in your Channel block:

Channel you@example.com
Far :you@example.com-remote:
Near :you@example.com-local:
Patterns *

2. Exclude specific folders by prefixing them with !:

Patterns * !Junk !Trash

3. Run mbsync -a and confirm the excluded folders are no longer synced.

Expected result: all folders sync except the ones you excluded.

Include Only Specific Folders

1. List only the folders you want:

Patterns INBOX Sent Drafts

Expected result: only the named folders are synced.

Exclude Gmail System Folders

Gmail exposes virtual folders under [Gmail]/ that can cause duplicate downloads.

1. Exclude the heavy ones:

Patterns * !"[Gmail]/All Mail" !"[Gmail]/Important" !"[Gmail]/Starred"

Expected result: Gmail labels sync without pulling redundant copies from All Mail.

Limit the Number of Messages per Folder

1. Set MaxMessages on the Channel to keep only recent messages locally:

Channel you@example.com
Far :you@example.com-remote:
Near :you@example.com-local:
Patterns *
MaxMessages 1000
ExpireUnread no

MaxMessages keeps the most recent N messages in the local store. ExpireUnread no prevents unread messages from being expired even if they fall outside the limit.

Expected result: each folder holds at most 1000 messages locally; older messages remain on the server.

Control Deletion Behaviour with Expunge

1. Set Expunge to control when deleted messages are permanently removed:

Expunge Both

Value	Behaviour
Both	Remove deleted messages from both local and remote
Near	Remove deleted messages from the local store only
Far	Remove deleted messages from the remote server only
None	Never permanently remove deleted messages during sync

Expected result: deletion propagation matches your preference.

Sync a Single Channel

1. Name your channels and sync one at a time:

mbsync you@example.com

Expected result: only the named channel syncs, which is faster when you have multiple accounts.

List Available Remote Folders

1. Run mbsync in list mode to see what the server offers:

mbsync -l you@example.com

Expected result: a list of all remote folders, which helps you decide what to include or exclude in Patterns.

Verify Your Configuration

1. Run mbsync in dry-run mode to preview what it would do:

mbsync -n -a

Expected result: mbsync prints the actions it would take without making changes.

See Setting Up Offline Email with mbsync for the full setup tutorial.