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Hmm, has RFC 2822 been superseded?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.