The cURL error 28 issue indicates a timeout occurred when your site attempted to make an HTTP request to the server.
cURL error 28 often occurs if your server fails to respond to your chosen mailer’s request timely.
Since it is mostly server related, it can happen if your server’s firewall is blocking requests from your SMTP plugin.
When this happens, you’ll likely see an error message that reads, ‘cURL error 28: Operation timed out after 5001 milliseconds with 0 bytes received.’
Resolving the Error – Solution
This error is usually not caused by the SMTP plugin you’re using. So resolving it would require making changes to your website’s server configuration. We’ll cover some of the troubleshooting steps to resolve the issue.
Update Your Software
Before going any further, ensure your site uses an updated version of PHP and cURL. An outdated software could lead to server timeouts. We recommend contacting your web hosting support to assist with updating your software.
Your hosting server could have a firewall feature that blocks requests from your SMTP server. You can temporarily disable firewall protection on your site to see if this resolves the issues. If you can’t find the firewall settings on your server, contact your web hosting support for guidance.
Server Timeout Limit
If your server has a low timeout limit, most requests that exceed the threshold set by your host will result in the timeout error. To accommodate requests from your SMTP plugin, you’ll need to increase your server’s HTTP request limit. Please get in touch with your web host if you need help increasing this limit.
Contact Your Web Hosting Support
If none of the troubleshooting methods above resolve the issue on your site, consider contacting your web host for additional support. Since the error is likely server-related, they should be able to resolve it.