When email won’t send, check connection, file size, storage, service status, and SMTP settings before trying app or device resets.
Stuck messages are maddening, whether you hit Send from a phone, a desktop client, or webmail. This guide walks you through quick checks and deeper fixes that clear an Outbox, prevent repeats, and keep messages moving.
Quick Checks Before Anything Else
Run through these basics first. They solve most send failures without digging into menus.
- Open a web page to confirm you’re online. If you’re on mobile, toggle Airplane Mode off and on.
- Retry with a short plain-text message to one address. If that works, the last email likely hit a limit or filter.
- Remove or shrink attachments. Compress images, share a cloud link, or send files in separate emails.
- Check mailbox and cloud storage. A full quota stops new mail from leaving.
- Glance at your provider’s status page to rule out an outage.
Symptoms And Fast Fixes
| Symptom | Likely Cause | Fast Fix |
|---|---|---|
| Message stuck in Outbox | Offline, add-in glitch, attachment too large | Go online, disable add-ins, trim file size, resend |
| “Message not sent” banner | Weak connection or app hiccup | Reconnect Wi-Fi or data, force-quit the app, retry |
| Bounce or “Delivery failed” notice | Recipient address error or recipient server block | Correct the address, ask contact to check Spam, try later |
| No error, nothing arrives | Mailbox full, filter moved mail, slow server | Free space, review filters, wait for a delay notice |
| “Authentication failed” | Wrong password, 2-step sign-in, app password needed | Re-enter password, add an app password, relogin |
| “Cannot connect to server” | Wrong SMTP host, port, or TLS setting | Use the submission port and correct security (see table below) |
| Only big emails fail | Attachment limit reached | Compress files or share via cloud storage |
| Webmail sends, app doesn’t | Broken profile or cached settings | Remove and re-add the account in the app |
If you use Gmail on the web and a message seems delayed or missing, Google’s “email I sent was delayed or didn’t arrive” guide lists sender-side steps and what to expect from bounce notices.
Email Not Sending: Fixes That Work
1) Confirm Network Access
Switch between Wi-Fi and mobile data. If a VPN is active, pause it. Some networks block outbound mail or certain ports. Try a different network to isolate the issue.
2) Check Service Health
When a mail service has a hiccup, sending fails across devices. Look for a green status on your provider’s dashboard or social feed. If the outage is widespread, waiting beats repeated retries that clog your Outbox.
3) Right-Size Attachments
Email isn’t built for huge files. Use image compression, split files, or a share link from your cloud drive. Many clients stall on single messages with oversized media, which leaves them parked in the Outbox until you edit or delete them. Zipping a folder helps, but cloud links with expiry and access controls are safer for large handoffs and reduce resend loops.
4) Clear The Outbox, Then Resend
Open the Outbox, edit the stuck message, and press Send again. If it refuses to budge, move it to Drafts, reopen, strip attachments, and try once more. This resets the send attempt without losing your content.
5) Free Up Space
Low storage on your device or a full mailbox blocks new mail. Empty Trash and Spam, delete giant threads with attachments, and clear space in your cloud account if your provider counts it toward email.
6) Re-enter Credentials
Changed your password recently? Re-authenticate in every mail app you use. With accounts that use two-step sign-in, some desktop clients need an “app password.” If you see repeated prompts, remove and re-add the account to refresh tokens.
7) Use The Correct SMTP Settings
Modern mail apps submit outbound messages on the submission service, not the old relay port. That usually means port 587 with STARTTLS, or port 465 with implicit TLS, both of which encrypt the link from your device to the server.
8) Test In Safe Mode Or A Fresh Profile
Desktop clients can misbehave when add-ins or corrupted profiles get in the way. Create a new profile, disable add-ins, then test sending. If the new profile works, migrate your data and retire the old one.
9) Try Webmail
Send the same message from your provider’s webmail. If that goes through, the issue lives in your app or device. If webmail also fails, the service or account needs attention. Private browsing mode can help.
Platform-Specific Tips
Gmail On The Web
Check the Sent label, then look for a bounce or delay notice. Review Filters and Blocked Addresses, storage usage, and recent security alerts. Google documents common delivery outcomes and what each notice means in its help page linked above.
Outlook For Windows Or Mac
Messages that hang in the Outbox often clear after you work offline, restart Outlook, and resend. Microsoft’s official Outlook help page lists additional steps, including fixing profiles and checking mailbox storage. See the “can’t send or receive messages in Outlook” article.
Apple Mail On iPhone Or iPad
Confirm the account is enabled under Mail settings, verify the outgoing server is selected, and toggle the account off and back on. If the app displays “Cannot Send Mail,” re-enter the password and try a different network. Apple’s guidance covers these steps and more for iOS and iPadOS. If the problem repeats, reset network settings, remove any old SMTP entries, and try sending from a different Wi-Fi network to rule out router quirks that block submission ports.
Attachment, Addressing, And Timing Pitfalls
Mind The Address Line
One wrong character bounces a message. Use autocomplete with care, and remove stale addresses from a contact card. If you’re mailing a group, send a tiny test to yourself first to avoid wide bounces.
Keep Messages Lean
Rich signatures, massive embedded images, and pasted screenshots inflate payloads. Trim signatures, downsize inline images, and paste links instead of full-size graphics when possible.
Give It A Minute
Busy servers queue mail. If your previous attempts fired rapidly, wait before retrying. Repeated sends can trigger rate limits, which delays everything you try to send for a short window.
Correct SMTP Ports And Security
Use these well-known options when you must enter settings by hand. Your provider’s exact hostnames can differ, but the port and security pairing below holds across modern providers.
| Purpose | Port | Security |
|---|---|---|
| Submission (recommended) | 587 | STARTTLS (TLS on connect after STARTTLS command) |
| Submission (implicit TLS) | 465 | Implicit TLS from the first packet |
| Legacy relay (often blocked) | 25 | No TLS by default; not for end-user submission |
Port 587 is defined for message submission and supports authentication with transport encryption; port 465 offers TLS from the first byte. Port 25 is for server-to-server relay and commonly blocked on consumer networks.
Deep Dives That Save Time Later
Clean Up Filters And Rules
Rules that move mail on arrival can also catch your own messages, hiding copies you expect to see in Sent or Inbox. Review rules that forward, auto-file, or delete. Pause them while you test. If you use forwarding across accounts, turn it off briefly to prove the path is clean end-to-end.
Review Security Extras
Antivirus email scanning, firewall rules, and privacy add-ons sometimes block outbound connections. Turn them off temporarily, send a test, then re-enable and add an allow-list entry if needed.
Rebuild Or Reinstall
If nothing works, remove and re-add the account, then rebuild the app’s cache or profile. Fresh configs clear stale tokens and broken settings that a restart can’t touch.
Quick Recap And Next Steps
Start simple: verify connectivity, try a tiny plain-text note, and trim attachments. Check storage, resend from webmail, and confirm the SMTP submission settings match the table above. If a client-specific fix is needed, use the official Gmail guide linked earlier or Microsoft’s Outlook help page for walk-throughs.