[icebraining]

I don't know what IANA decided; all I know is the TLDs I listed do have A records, and they load at least on Firefox, so there's obviously no technical reason the new TLDs can't.

You should also note that email addresses that doesn't have a '.' in the host part are technically invalid, i.e. me@mytld is not a valid fully qualified email address.

Hmm, has RFC 2822 been superseded? Because it clearly says the domain part can be a dot-atom, which is defined in the same RFC in ABNF form as:

    dot-atom        =       [CFWS] dot-atom-text [CFWS]

    dot-atom-text   =       1*atext *("." 1*atext)

As you can see, the dot (".") is enclosed in a section of variable repetition (*) with no minimum number of times, so it can not appear at all.

[tankenmate]

I suspect those A records are probably grandfathered and they are of course ccTLDs so the rules are different. None of the gTLDs have A records for their TLD (although they almost certainly have glue A records). From memory I queried John Craine (ICANN Security, Stability and Resiliency Director) about this a number of years ago and again if I remember accurately his response was that they wouldn't allow any additional types of records. I suspect this is a policy decision rather than a technical one.

RFC 2822 has been superceded by RFC 5322. The problem is not being allowed to put MX records in the zone for a TLD, and hence the mail is not routeable. Also remember that you would need to differentiate between "me@mytld<.localdomain>" and "me@mytld.", I'm not sure if all MTA software (let alone MUA) will do the right thing with differentiation. This is probably considered to impact stability and hence is discouraged.