Gmail IMAP Bandwidth Limit Exceeded: What It Means

When an IMAP client shows a 'bandwidth limit exceeded' or 'account has exceeded bandwidth limits' error from Gmail, it means the account's daily IMAP download quota has been hit. The message lands most often when you first add a Gmail account to a desktop client, run a migration tool, or point a backup application at a large archive.

The throttle is temporary, not permanent. Understanding what the quota measures and how the cooldown clock works is the fastest way to get sync moving again without making things worse.

The short answer#

Gmail limits how much message data an IMAP client can download in a rolling 24-hour window. The exact byte ceiling is not published, but Google's IMAP developer documentation and third-party measurement both confirm it exists per account. When a client crosses it, Gmail returns an error — 'bandwidth limit exceeded' or a variant — and rejects further IMAP connections until the window resets.

The lockout usually lifts in 24 hours. Severe over-runs, such as a migration tool pulling gigabytes in one pass, can extend the block to 48 or 72 hours. Restarting the client, removing and re-adding the account, or generating new app passwords does not help during an active lockout and may restart the enforcement window.

Before you start: what the quota actually measures#

Gmail's IMAP rate limits sit in two distinct layers, and it helps to know which one you have hit.

The bandwidth quota measures cumulative data downloaded — message headers, bodies, and attachments — across all IMAP connections for the account in a rolling window. Hitting it is what produces the 'bandwidth limit exceeded' error. The connection limit, separately, caps how many simultaneous IMAP sessions the account can hold open at once. Exceeding that produces 'too many simultaneous connections.' Both errors cause a throttle, and mail clients sometimes surface them with the same or similar wording, which adds confusion.

What causes the limit to trip#

The quota is designed to catch bulk download behaviour, not normal daily use. Most accounts never approach it during regular email activity. The error almost always appears in one of these situations.

Steps to get sync moving again#

Work through these in order. The most important step is the first one: stop the traffic that hit the quota before doing anything else.

1. 1

   Stop the downloading client

   Close the mail client, pause the migration tool, or disable the backup job that triggered the error. Leaving it running while the account is throttled means the client keeps retrying, which does not reset the limit and may extend the enforcement window. Every reconnect attempt counts.

2. 2

   Wait for the quota window to reset

   Gmail's bandwidth quota resets on a rolling 24-hour basis. Do not try to work around the lockout by creating a new app password, removing and re-adding the account, or switching to a different client — the throttle is on the account, not the credential or the app. Most accounts recover in 24 hours; plan for up to 72 hours if the over-run was large.

3. 3

   Confirm IMAP is still enabled in Gmail

   Occasionally the lockout prompts a client to display a generic authentication error rather than the quota message, which makes it look like IMAP is disabled. Verify in Gmail settings: open Settings, Forwarding and POP/IMAP, and confirm IMAP access is set to Enable IMAP. If it is already enabled, leave it as-is — toggling it off and back on does not clear the throttle.

4. 4

   Reduce the sync scope before reconnecting

   Before you open the client again, change its IMAP sync settings to limit what it downloads. In most desktop clients this means setting the sync range to the last 30 or 90 days and deselecting large label folders such as All Mail and Spam. For Gmail specifically, avoid subscribing to All Mail in the IMAP folder list — it duplicates every message and is the single largest contributor to bandwidth.

5. 5

   Reconnect with rate limiting in place

   Once the window has reset and the sync scope is reduced, reconnect the client. For migration tools, add throttling flags before restarting: imapsync supports --sleep to add a delay between messages and --maxsize to skip large attachments. For backup tools, look for download rate or concurrent-connection limits in the settings. Let the first sync complete at the reduced scope before expanding it.

How limits differ across clients and use cases#

The same Gmail account behaves differently depending on how each client or tool approaches its initial sync. Knowing the default behaviour of your client is what lets you pre-empt the quota rather than hit it.

What to do when it does not resolve after 24 hours#

If the account is still returning a bandwidth error after a full day, work through these checks before escalating.

• Confirm the client or tool is genuinely stopped. A background service or scheduled task running under a different process name may still be issuing IMAP connections. Check your operating system's process list and network activity.
• Check for multiple simultaneous sync sources. If the account is connected on a phone, a tablet, a laptop and a desktop, all running independent syncs, the aggregate bandwidth from all four may be keeping the account over its limit continuously. Disconnect all but one client while the lockout clears.
• Look for the All Mail label in your IMAP folder subscription. Most desktop clients subscribe to All Mail by default, which means every message in the archive is downloaded once as its label and again as a copy in All Mail. Unsubscribing from All Mail in the client's folder list before reconnecting cuts download volume roughly in half for a large mailbox.
• For Google Workspace accounts, contact your domain admin. Workspace admins can view IMAP access logs in the Admin console and can apply per-user IMAP bandwidth policies. If you are sharing an account across many users, the admin may need to restructure access.
• If the error persists beyond 72 hours and none of the above applies, open a support case with Google. Consumer Gmail accounts can use the Help Center; Google Workspace accounts have admin-level support channels.

A faster way: clients that sync incrementally by default#

The bandwidth quota exists because IMAP gives a client no natural way to download only what changed — a naive client fetches everything, every time it needs to know the state of the mailbox. The workaround is configuring a shorter sync window before connecting, which is easy to miss in a first-time setup.

We build AI Emaily, an AI-native email client that connects to Gmail via IMAP and OAuth. It syncs incrementally by default — pulling recent mail first and expanding the archive on demand rather than downloading the full account history in one pass. That means a new account connection is unlikely to hit the daily bandwidth ceiling even on a large mailbox. If you are evaluating clients specifically because a previous one triggered the quota, that is a differentiator worth looking for. You can see how the connection works on the connect-IMAP docs page or start a 7-day free trial at aiemaily.com.