Monobloc heat/aircon

Possibly - but if your email address (before the gmail bit) was guessable (e.g. myfirstname99 @ gmail dot com) then it could just have been a random computer-generated mailing.

Similarly businesses often use generic “info at” or “enquiries at” email accounts and those are much more prone to spamming as a result.

Except my real name email address has never suffered from spam. The one that did was the same but with 00 at the end.

Possibly … I prefer the theory that Trump buys spam email lists from whoever.