MX Toolbox might report bogus problems with testing a fully protected WHM domain. These warnings will take the forms of the following:
3 Problems
- Reverse DNS does not match SMTP Banner
- Warning – Does not support TLS.
- 15.290 seconds – Not good! on Transaction Time
In fact, all three are bogus. WHM has a protection level called “Delay SMTP connections” but you can bypass it by adding at least the following two IP addresses to Greylisting bypass:
- 18.205.72.90
- 18.209.86.113
- 52.55.244.91
What happens is MX Toolbox does an SMTP connection test, gets a timeout, and doesn’t quite know how to handle it producing these bogus problems.
To see if your fix worked, add those IP addresses and do email health again.