[feat] Separate MX for paid accounts

[ceonelson]

I have a paid account with FE and tried to sign up for an account with https://short.io/

I received this error message:

I was using my business email (hosted by FE)... tried all of my other emails (all hosted with FE) and got the same message. Finally I tried my gmail account and was able to sign up.

I believe the error was given because they checked the MX entries for the email domains I provided, and saw FE so (rightfully) assumed that it was a disposable email address.

I reached out to their support after signing up and made them aware of their validation being incorrect, but on the FE side having a separate MX domain for paid subscribers would likely solve the issue :)

[ceonelson]

That being said, these disposable email checker websites correctly determined one of my paid FE email addresses was valid:
https://unwrap.email/
https://quickemailverification.com/tools/disposable-email-address-detector

[ceonelson]

This one failed my paid PE address:
https://www.zerobounce.net/free-email-verifier/

[titanism]

We do not plan to have separate MX servers for paid accounts. Most of these do it at the root domain level, which would not make it possible to do subdomains or multiple IP's to work around false positives. It is better to manually help curate those disposable lists (as you have done) and keep our service off of them. As we grow, it will be less likely to happen.