Gmail bounce: 5.1.1 no such user, or 5.7.26 failed SPF

Part of our guide on apps keep crashing after android update samsung

The reason your email failed is sitting in one line of the bounce message, and almost nobody scrolls down far enough to read it.

Why emails bounce from Gmail

Say you fire off a newsletter from the Gmail app on your phone, and twenty minutes later a message from mailer-daemon lands back in your inbox. You half-read it, assume Gmail is broken, and try again tomorrow. The same bounce returns.

That bounce is not noise. Buried in it are the receiving server's status code and an explanation of the failure. Reading those lines takes thirty seconds.

Common causes include bad addresses, full mailboxes, domain authentication failures, sending limits, account security checks, and phone or network trouble.

On a phone there are two extra wrinkles. The Gmail app sometimes hides the technical part, and some bounces never arrive because the sending app times out. The fixes below cover both. For the detail, see our notes on steps to locate lost phone.

• Bad address: a typo, a closed account, or a contact you have not emailed in years. Code 5.1.1.
• Full mailbox: the recipient's storage is maxed out. Code 5.2.2.
• Custom domain authentication: SPF, DKIM or DMARC records missing or misaligned. Code 5.7.26.
• Sending limit hit: personal Gmail and Google Workspace have separate daily limits. Google lists the current limits by account type in its [official sending limits guide](https://support.google.com/a/answer/166852).
• Flagged account: Gmail throttles an account showing signs of compromise or mass sending. Often a 4.x.x or a generic abuse notice.
• Phone or network trouble: a third-party mail app with wrong SMTP settings, a huge attachment, or a hotel or carrier network blocking outbound mail on port 25.

Find the bounce and its diagnostic code in the Gmail app

Picture a freelancer emailing a client list from an iPhone on a train. Nothing seems wrong until she checks later and finds the replies are fine but a message titled 'Address not found' sits in her inbox. That message contains the useful details, if she knows where to look.

Search your Gmail for from:mailer-daemon. Bounces can also hide in Spam or Promotions, so check both folders before you assume nothing bounced. The sender line usually starts with Mail Delivery Subsystem.

Open the message and expand 'Message clipped' or tap the three-dot menu to show everything. Scroll down to the block headed Diagnostic information for administrators. The line you want reads something like: smtp; 550 5.1.1 <name@example.com>: recipient address rejected. There is more on setting up text and email alerts in a separate guide.

Copy that line into a note if you plan to contact support. Record the code, receiving server name, and recipient address.

1. Open Gmail and search from:mailer-daemon.
2. Check Spam and Promotions too; bounces land there more often than people expect.
3. Open the bounce and tap the three-dot menu to expand the full text.
4. Scroll to 'Diagnostic information for administrators'.
5. Note the code starting 5 or 4, the recipient address and the receiving server.

Read the code: 5.1.1, 5.2.2, 5.7.26 or a 4.x.x deferral

The first digit separates permanent failures from temporary ones. A 5 means the specific delivery failed, while a 4 means the receiving server asked you to try again later.

Treat a 5.x.x error as a problem to correct before another attempt. Let a 4.x.x error cool down, then resend once rather than hammering the receiving server. People in this spot often ask about set friendly network name android as well.

The remaining digits narrow the cause. 5.1.1 and 5.2.2 concern the recipient, while 5.7.26 usually concerns authentication for the sending domain.

Fix 5.1.1 and 5.2.2: bad address or full mailbox

A 5.1.1 means the receiving server looked for that mailbox and found nothing. Typos are the common case: an extra letter, a dot where none belongs, or gmail.con instead of gmail.com. Retype the address fresh rather than trusting autocorrect, then send once.

If the spelling is right and it still bounces, the account is closed. That happens a lot with old work addresses and lapsed student accounts. There is nothing to fix; the contact is gone. We go through phone keeps rebooting android step by step elsewhere on the site.

A 5.2.2 is different. The mailbox exists but the recipient has hit their storage limit, which is common on free accounts with large photo backups. Wait a day or two and resend once. If it bounces again, message them through another channel.

If you keep a list of contacts and several addresses bounce this way, it is time to clean the list rather than email around the holes. Resending to dead addresses teaches receiving servers that your domain mails invalid accounts, and that reputation cost follows every future message you send.

This is the point where a validation tool earns its keep if you send at any volume. ZeroBounce checks a list before you send, flags addresses that will hard-bounce, and marks risky or catch-all ones so you can decide. It will not rescue an address that is genuinely dead, and if you email a dozen friends a month you do not need it. Its free tier lets you test the idea on a small list first. People in this spot often ask about fix greyed out apps issue as well.

Fix 5.7.26: your custom domain fails SPF or DKIM

A 5.7.26 bounce means receiving servers cannot verify your custom domain. They treat the message as possible spoofing and refuse it. Personal Gmail cannot correct missing DNS authentication for your domain.

Publish SPF, DKIM, and DMARC records in your domain’s DNS. SPF lists approved sending servers. DKIM signs messages. DMARC tells receiving servers what to do when authentication fails.

For Gmail “send as” addresses, check Gmail on the web under Accounts and Import. Confirm the alias, password, and verification status. Remove any unfamiliar alias and review account security.

Google’s setup instructions are [SPF](https://support.google.com/a/answer/106850) and [DKIM](https://support.google.com/a/answer/180504). Add DMARC in your DNS provider’s control panel.

Send a test to Gmail or Outlook. Open the message on the web, choose Show original, and check SPF, DKIM, and DMARC for PASS results.

1. Open the DNS records for your domain.
2. Add one SPF record including every approved sender.
3. Enable DKIM in the Google Workspace Admin console and publish its key.
4. Add DMARC with a monitor-only policy first.
5. Wait for DNS changes, often under an hour, then check Show original.

Gmail's sending limits and a flagged account

Picture a student who imports club members into a contact group and hits send from a personal Gmail account. The messages stop, and the error mentions limits or unsolicited mail. Nothing is necessarily wrong with the addresses; the account may have reached its daily allowance.

Personal Gmail has daily sending limits, and Google Workspace has separate limits. Google changes limits and applies them according to account type, recipient count, message pattern, and recent activity. Check the [official Google sending limits guide](https://support.google.com/a/answer/166852) for the current limit that applies to your account.

The limits count activity across the relevant account rather than giving every individual message a fresh allowance. Split a legitimate send only when Google's guidance permits it, or use a bulk-sending service for campaigns.

Google's bulk-sender rules matter more each year. Large volumes without SPF, DKIM and DMARC aligned, or without one-click unsubscribe, get deferred or filtered even when every address is valid. A 4.x.x deferral on a big send is usually this.

Bounces to addresses you know are fine deserve a security check. Open myaccount.google.com, review recent sign-in activity and connected devices, and look at the 'send as' list for aliases you never added. Change the password and turn on two-step verification before doing anything else.

If the bounces came after a sudden spike in volume, Gmail's mass-sender protection is likely throttling you. Slow down and compare your activity with the account-specific guidance before sending again.

Phone-specific causes: SMTP, attachments and blocked networks

An iPhone Mail message stuck in the outbox points to the app, network, or outgoing server. Send the same message from Gmail on the phone and from a desktop browser. One working path identifies the faulty device or app.

Non-Gmail accounts need the correct SMTP server, port, authentication, and password. Two-step verification usually requires an app password. Re-add the account so the app can fill its settings correctly.

Hotel Wi-Fi, office networks, and some carriers block SMTP ports. Switch to mobile data or another Wi-Fi network. A working data eSIM can bypass hotel Wi-Fi, but only on eSIM-compatible phones.

Gmail rejects attachments over roughly 25 MB. Share a Drive or cloud link instead. If the message bounces on two networks, fix the account settings, not the phone.

How to stop it happening again

Remove an address after one hard bounce. Stop mailing contacts with no opens for a year or more. Dead addresses and weak engagement both damage delivery.

Personal Gmail and Google Workspace have daily sending limits, but the applicable limit depends on account type and sending activity.

Google lists current Gmail and Google Workspace limits in its [official sending limits guide](https://support.google.com/a/answer/166852). Check it before planning a large send. Don’t rely on an old figure copied from another account type.

Send a quarterly test from two networks. If you mail hundreds of contacts, validate the list before each campaign. Review sign-ins and “send as” aliases monthly.

Questions people still ask

I have lost hours to bounces I never scrolled down far enough to read. The diagnostic line has saved every one of them since.