Just to be clear - although i said "SPAMMER" I was really referring to legitimate newsletters that I just don't want to hear from anymore.
Many of them add me because, yes, they think I am a travel agent, or they know I write articles. Or it was just something I bought online and they "take the liberty" of adding you.
In any case - I know not to unsub from real spammers, but I don't get real spam anymore since we migrated our mail to use the GOOGLE mail servers - they have GREAT SPAM FILTERs. If I ever want to see it I can go into the "junk" folder, but it works so well I never even have to check in there.
But a legitimate newsletter - like ours - if you ever wish to unsubscrube the process is easy - you just follow the link on the newsletter. So, I do unsubscribe from honest newsletters - but some of them do send these stupid follow up letters.