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✉️ Email Delivery

Documentation, reference material and tutorials for CRM-NG SMTP Email: setup guides for every mail service, troubleshooting, and one article per error message.

Error: Connection timed out (code 110)

Updated

By Duane GarnerChief Executive Officer (CEO)
Summarize: Claude ChatGPT View Markdown
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Your server waited for the mail server or API and got no answer. Usually a blocked port or firewall; sometimes a slow or unreachable service.

Shown by every mailer (SMTP mailers as code 110, API mailers as cURL error 28)

The test result or the error log shows Connection timed out (110), cURL error 28: Operation timed out after ... milliseconds or another message with "timed out" or "timeout".

This article is for site owners whose send attempt waited and then gave up. Other SMTP and Zoho Mail report it as error 110; API mailers such as SendLayer, Brevo, Mailgun or Amazon SES report it as cURL error 28.

What this error means

Your web server sent a request to connect and heard nothing back before the waiting time ran out. Unlike "connection refused", no one said no; the request simply disappeared. That pattern almost always means a firewall is silently dropping the traffic, or the remote service could not be reached at that moment.

Common causes

  • Your web host silently blocks outgoing SMTP ports (25, 465 or 587). This is the most common cause for Other SMTP.
  • The wrong SMTP Port, on a server that ignores connections on unused ports.
  • A firewall on your server, or at the mail provider, dropping your server's IP.
  • Your server's network or the provider's service is having trouble. API timeouts are often short-lived for this reason.
  • Your server has no working IPv6 route but the host name resolves to an IPv6 address first.
  • A very slow DNS lookup on the server that eats up the waiting time.

How to fix

  1. Check the provider's status

    Look at your mail provider's status page for an outage. If there is one, wait and test again later.

  2. Check port and encryption

    For Other SMTP, go to CRM-NG SMTP → Settings → General and confirm SMTP Host, SMTP Port and Encryption match your provider: 465 with SSL, 587 with TLS. Save and test.

  3. Try the other port

    Switch between 587 and 465 (changing Encryption to match). One may be open when the other is not.

  4. Ask your web host

    Ask whether outbound connections to your mail server, or to the API host, are blocked or rate-limited, and whether IPv6 works. Share the error from CRM-NG SMTP → Tools → Debug Events.

  5. Send a test

    Go to CRM-NG SMTP → Tools → Email Test, fill in Send To and press Send Email.

Verify it worked

The test page shows "Test email sent successfully! Check your inbox to confirm delivery." For intermittent API timeouts, watch the Email Log for a day to confirm failures stop.

Notes

  • If your host blocks SMTP ports, switch to an API mailer, which uses HTTPS on port 443.
  • Optimize Email Sending on CRM-NG SMTP → Settings → Misc sends in the background, so a slow mail service does not slow your pages.
  • A backup SMTP transport on the Alerts tab can carry mail when the main mailer times out.
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