HOWEVER, there are many issues with this site that will cause messages to get marked as spam with a high frequency (including my innocuous test message to a gmail address).

1) There's no recommendation to setup SPF for your domain. This is the big one. SPF is a big deal, and not having any spf will give you a higher spam score.

2) The creator of this service did not setup a reverse dns entry for the ip to the mx domain. There's no reverse dns at all (even though he's hosted with ramnode and ramnode supports rdns).

3) The creator does not allow you to add dkim signing keys; you can't dkim sign your messages.

The above factors ensure that google has a high chance of marking you as spam, as well as any other sufficiently strict spam software. amavisd did not mark it as spam for me, giving it only a spam score of a little over 2, though I have mine configured at a high threshold compared to many people.

Because of the above reasons, I wouldn't consider using this. The lack of a rdns entry is especially unforgivable because it's so easy and helps with your spam rating so much. The other factors are all additional complexity because the owner of the domain (user) would have to do additional work beyond the dns record, but those should also be there.

Perhaps the creator will see this and improve these problems.

However, you have a good point. It would probably not be the ideal name for a service like to GMail, in which all users live under the @gmail.com domain.

The parent comment is not correct in thinking that matters, but they are correct that it will be identified as pawnmail, just not as part of the email address itself.