Disinformation, doesn't actually help, if you blacklist based on destination IP and MX entries. Using alternate domain won't help, unless you also run TCP proxy or forwarding SMTP server. Even using different IP and name with light TCP relay proxy, gets revealed during handshake.
Of course you can add alias to your own mailserver and domain(s) alias to your own mailbox or set forwarding to mailinator. Then it's quite hard to find out if messages are really sent to mailinator or your own real mailbox.
The only time I remember being blocked from using a mailinator email it was a client side regex form validation - using one of Mailinator’s "alternate domains" got around that.
I would suspect that a lot of companies are willing to add a JS regex to their form validator, but are not willing to add SMTP headers sniffing to their validator. That barrier means that much of the time a simple domain name change will work.
The GPs comment is not unhelpful, and certainly not "Disinformation". It just isn’t completely reliable. Sometimes it will work, sometimes it won’t depending on how motivated the author of the validation is.
Burp, nuff said: "220 mail.mailinator.com ESMTP Postfix"
Also see: https://ssl.trashmail.net/forum/viewtopic.php?f=2&t=5421#p78...
Of course you can add alias to your own mailserver and domain(s) alias to your own mailbox or set forwarding to mailinator. Then it's quite hard to find out if messages are really sent to mailinator or your own real mailbox.