The relay address does not show as valid on email validators. eg: ipqualityscore dot com and others list it as invalid and disposable even though it does get forwarded.

The problem does not lie with ipqualityscore dot com or others. The problem is with the service which validates the email. Here is the conversation using another validator called centralops dot net.

THE CONVERSATION with https :// centralops.net /co/ ---> The address was rejected! Done today 18-May-2022 12:24 UTC-4

How is any email validating service suppose to reply but "invalid"? "Disposable" email is a judgement call.

OK, I use the free service so I can't complain but if I were to contemplate getting the paid version there is not much incentive to do so if the email will check out as invalid.

Now if you use this email address and the site checks the validity of the email (as it should to avoid spam) then it will see an invalid email

Validating .........@mozmail.com...
Validation results
confidence rating: 0 - Bad address
error : RecipientRejected - Mail server rejected the email address.
canonical address: <.........@mozmail.com>
MX records
preference exchange IP address (if included)
10 inbound-smtp.us-west-2.amazonaws.com
SMTP session

[Resolving inbound-smtp.us-west-2.amazonaws.com...]
[Contacting inbound-smtp.us-west-2.amazonaws.com [54.240.250.228]...]
[Connected]
220 inbound-smtp.us-west-2.amazonaws.com ESMTP Amazon SES OenPjqnXlNNRjaYTNPLg
EHLO mx1.validemail.com
250-inbound-smtp.us-west-2.amazonaws.com
250-8BITMIME
250-STARTTLS
250 Ok
MAIL FROM:<>
250 Ok
RCPT TO:<.........@mozmail.com>
550 5.7.1 TLS required by recipient
[Address has been rejected]
RSET
250 Ok
QUIT
221 Bye
[Connection closed]