Using a cPanel server? Getting “Timeout waiting for response after 15 seconds” error or exclamation mark on some SMTP tests on MXtoolbox?
It’s quite easy to fix. First of all, you have to login to WHM and to Exim Configuration Manager. Find the “Introduce a delay into the SMTP transaction for unknown hosts and messages detected as spam” option and set it to “off”.
Now, your SMTP test should look something like this: