When Gmail won't send, work through six checks in order: connection, storage, attachment size, sending limits, account security, and Google's own status. The first three are free and take two minutes. The fourth and fifth are the ones that matter for anyone sending outreach, because a limit or a revoked connection stops mail without a clear error. Then deal with what didn't go, so you don't double-send.

Most guides to this problem were written for someone whose phone is stuck on "Queued." They suggest clearing the app cache and turning on background data. That fixes a phone. It doesn't help if you send 30 emails a morning through a tool connected to your Gmail and none of them went out on Monday. This checklist covers both.

First, name what you're seeing

The fix depends on which of four things is happening.

  • The message sits at "Sending..." or "Queued," or in the Outbox. Gmail accepted it and can't deliver it to Google's servers. Usually connection, storage or size.
  • A banner says "Message not sent" or "You have reached a limit for sending mail." Gmail refused it. Usually a limit or a security hold.
  • A tool you use says it sent, and the Sent folder is empty. The connection between the tool and Gmail is broken.
  • The email was sent, and a bounce came back minutes later. That's a delivery problem, and Gmail message not delivered: read the bounce, fix it is the page for it.

Check 1: the connection (one minute)

Open another website in the same browser. If it won't load, that's your answer. If it does, reload Gmail, and then try an incognito or private window. A browser extension that touches email or privacy can block sending, and a private window turns extensions off. In Chrome, Gmail also has an Offline setting under Settings, See all settings, Offline. If it's on, mail you write queues locally until it can sync, so turn it off to test.

Check 2: storage (one minute)

An account over its Google storage limit can neither send nor receive mail. The storage count is shared across Gmail, Drive and Photos, so a full Drive can silently stop your outreach. Look at the storage bar at the bottom left of Gmail, or in your Google account's storage page. If it's at or near 100 percent, clear large attachments (search "larger:10M" in Gmail) or empty Trash and Spam, then try again.

Check 3: attachment size and format (one minute)

Gmail's attachment limit is 25 MB in total. Past that, Gmail offers to turn the files into Drive links, and a connected tool may simply fail. A recipient's own limit is often lower, which shows up as a bounce rather than a stuck message. Outreach shouldn't carry attachments anyway: cold email with an attachment explains why, and what to link instead.

Check 4: sending limits and temporary holds (two minutes)

If the banner mentions a limit, you've reached Google's daily cap. It lasts up to 24 hours and nothing speeds it up. What to do when Gmail says daily user sending limit exceeded has the table of causes and the restart plan. If there's no limit message but sending stopped after a burst, treat it as a temporary hold, stop for a day, and restart at about half your old pace. The numbers behind a safe pace are in how many cold emails per day from Gmail.

Check 5: security prompts and revoked access (two minutes)

This is the one that hides. If you changed your Google password, turned on 2-step verification, or removed an app's access, every outside tool that sends through your Gmail can lose its connection without telling you. Anselm sells reconditioned office chairs and has a tool send 30 emails each weekday at 8. On Monday none went. He assumed the tool had failed. In fact he'd reset his Google password on Sunday, which signed the tool out. He lost three mornings, 90 emails, before he noticed. Check Google Account, Security, then "Your connections to third-party apps and services." If the tool isn't listed, reconnect it. Also open Gmail on the web and look for a banner asking you to verify it's you, or a security alert email from Google.

Check 6: when it's not you

Google publishes a status dashboard for Workspace services. If Gmail shows an incident, wait. If you use a custom domain with Workspace, also look at your admin console for a notice that mail routing is paused, which usually means a billing or domain issue. For a plain Gmail account, a second device on a different network is a good test: if the same message sends from your phone on mobile data, the problem is your computer or network.

What to do with the messages that did not go

Don't just hit Send again. First find out which ones left. Open Sent and search by recipient or by a phrase from the email. Then check Drafts and the Outbox. For a batch, compare your sheet to Sent: Anselm sorted his sheet by address and ticked off the 90 that were missing. Resend only those, and spread them over a few days rather than all at once, so you don't trigger the limit you were nowhere near. If follow-ups were scheduled for the days that passed, check they're not about to fire on a first email that never went. A follow-up to someone who never got the first message reads strangely, and it's easy to fix by pausing the sequence until the first email is out.

Preventing the silent stop

Two habits catch most of it. Look at the Sent folder once a day for the first week of any new setup, and look again whenever you change a password. And set a count: if you expect 30 sends by 9 a.m. and the number is zero, you want to know that at 9:05, not on Friday. The concepts behind who's allowed to send as you are in how to send cold emails from Gmail, and if mail leaves but doesn't arrive, cold email deliverability basics and cold email bounce rate take over. For a sender who's moving to a business address, Google Workspace vs Gmail covers what changes.

Rocketship sends from your own Gmail, and if that connection breaks, its daily brief puts a "Gmail is disconnected" warning at the top, so you don't find out on Friday. It finds the buyers, emails them, follows up, and books the meeting on its own. Plans that get you customers start at $24.99 a month (Launch), and every monthly plan starts with a 7-day free trial, card required. See how the AI workers run outreach.