Why is my email slow?
There are uncountable reasons why email may be slow, so CheckTLS cannot tell you exactly what is wrong with yours. But CheckTLS can show you exactly how much time each step of an email transfer is taking, so you know where to focus your efforts.
For example the below real-world test (the names have been changed to protect the guilty) shows an email server that is taking just over 20 seconds to issue the very first sign-on message (see hilite below).
"slow.com" is an email provider for multiple domains (including somewhere.com), and we suspect that slow.com takes a long time to figure out what it is supposed to do with email for somewhere.com.
CheckTLS does have all of the forward and backward DNS records properly configured for CheckTLS.com, so this server's issue is not in standard email verification DNS timeouts.
somewhere.com should show this to slow.com and demand they fix it. Or get a better email provider.
looking up MX hosts on domain "somewhere.com"
- mx.slow.com (preference:10)
|seconds||test stage and result|
|[000.113]||Connected to server|
|[020.271]||<--||220-mx.slow.com ESMTP Exim 4.89 #1 Sun, 03 Dec 2017 17:16:33 +0000
220-We do not authorize the use of this system to transport unsolicited,
220 and/or bulk e-mail.
|[020.272]||We are allowed to connect|
|[020.375]||<--||250-mx.slow.com Hello www4.checktls.com [126.96.36.199]
250-AUTH PLAIN LOGIN
|[020.375]||We can use this server|
|[020.376]||TLS is an option on this server|
|[020.483]||<--||220 TLS go ahead|
|[020.483]||STARTTLS command works on this server|
|[020.722]||SSLVersion in use: TLSv1.2|
|[020.722]||Cipher in use: ECDHE-RSA-AES128-SHA256|
|[020.722]||Connection converted to SSL|
|...rest of output deleted...|