iPhone and iOS email setup troubleshooting – SMTP authentication and port configuration
If you’re unable to send emails from your iPhone or iPad after adding your email account, the issue is almost always related to your outgoing mail (SMTP) server settings. This guide covers the most common causes of “Cannot Send Mail” errors on iOS and how to fix them.
Common Error Messages
- “Cannot Send Mail – The connection to the outgoing server failed”
- “Cannot Send Mail – A copy has been placed in your Outbox”
- “The user name or password for [server] is incorrect”
- “Unable to verify account information”
Correct SMTP Settings
Your outgoing mail server must be configured with the following settings:
| Setting | Value |
| SMTP Server | mail.yourdomain.com (or provided hosting server name) |
| Port | 465 (recommended) |
| SSL/TLS | ON (required) |
| Authentication | Password |
| Username | Your full email address (e.g. you@yourdomain.com) |
| Password | Your mailbox password |
Important: The username must be your full email address, not just the part before the @. This is the most common mistake.
Step-by-Step Troubleshooting
1. Verify Your Username
Go to Settings > Mail > Accounts > [Your Account] > SMTP and confirm the username is your complete email address (e.g. john@example.com), not just “john”.
2. Check the SMTP Port
Under your SMTP server settings, ensure the port is set to 465. If 587 was automatically added, update to 465. This require SSL/TLS to be enabled.
- Port 587 – STARTTLS (starts unencrypted, upgrades to TLS)
- Port 465 – Implicit SSL/TLS (encrypted from the start)
Do not use port 25, as unsecure Ports are usually blocked.
3. Enable SSL/TLS
Make sure “Use SSL” is toggled ON in your SMTP server settings. Without encryption enabled, the server will reject the connection on port 465.
4. Re-enter Your Password
Delete the saved password and re-type it carefully. Pasted passwords sometimes include invisible characters. If you’ve recently changed your mailbox password in your hosting control panel, your device will still have the old one stored.
5. Delete and Re-add the Account
If the above steps don’t resolve the issue:
- Go to Settings > Mail > Accounts
- Select the problematic account
- Tap Delete Account
- Re-add the account using Other (not the automatic setup options)
- Enter the correct SMTP settings manually as shown above
6. Check for Network Restrictions or RBL listings
Some networks IP have been blacklisted and therefore resulting in being blocked from connecting to the SMTP server outbound mail ports.
- You can check your Public IP for RBL listing through https://mxtoolbox.com/blacklists.aspx .
- If listed by SpamHaus and others, you can contact your network provider to work on removing listing OR reset the WIFI to be assigned a new IP from the ISP DHCP pool
- Test on mobile data or different Network to rule this out. If it works on mobile data but not Wi-Fi, the network traffic is being filtered by the Mail server.
- As a last resort, Contact Support to Temporarily Whitelist your IP
Why This Happens
iOS often tries to auto-detect mail server settings during account setup. When auto-detection fails or guesses incorrectly, it may default to the wrong port, omit SSL, or use only the local part of the email address as the username. Manual configuration resolves these issues.
Still Not Working?
If you’ve verified all settings above and outbound mail still fails, contact support with:
- Your full email address
- The SMTP server, port, and SSL setting you’re using
- A screenshot of the error message
- Whether the issue occurs on Wi-Fi, mobile data, or both