This is a bit embarrassing, but I accidentally sent an email to another spamgourmet user, a total stranger.
I was testing one of my email accounts, and meant to send an email to:
word.numberword.myusername@wronghead.com
But by mistake I left off my spamgourmet username, so I sent the email to:
word.numberword@wronghead.com
Since numberword is a common English word, I thought there was a good chance it was someone's username, so I sent another email explaining and apologizing for my mistake. Then out of curiosity I tried to register numberword, and indeed it is already taken.
So what is the protocol when this happens? Send an apology like I did, or just move along and not risk upsetting them with a second email?