Troubleshoot IMAP Performance

Prerequisites

1. You can connect to your IMAP server with NeoMutt.

2. You can reproduce the slowdown (opening a mailbox, checking for new mail, or searching).

Reduce Polling Overhead

1. Tune the global polling intervals:

set mail_check = 90
set timeout = 15

Expected result: NeoMutt checks for new mail less frequently, reducing idle overhead.

Avoid Hanging Connections

1. Ensure keep-alives are frequent enough for your server:

set imap_keep_alive = 300

Expected result: servers are less likely to disconnect idle sessions.

Disable IMAP IDLE if It Freezes

1. If the UI stalls while waiting for new mail, disable IDLE:

unset imap_idle

Expected result: NeoMutt uses polling instead of IDLE, which can be more reliable on some servers.

Limit Large Fetches

1. If opening large mailboxes times out, fetch headers in chunks:

set imap_fetch_chunk_size = 200

Expected result: header downloads are split into smaller requests.

Enable Compression

1. If bandwidth is a bottleneck, enable IMAP compression:

set imap_deflate = yes

Expected result: large mailbox operations use less bandwidth.

Reduce Connection Churn

1. Avoid opening new IMAP connections just to check mail:

set imap_passive = yes

Expected result: NeoMutt only checks mail over existing connections.

See How to Set Up IMAP and IMAP Variables for full details.