Well, I just happen to be a mail server admin, so I can tell you a little about this, and a odd coincidence as well.
I am a small ISP, and take great efforts on a daily basis to prevent spam from coming to my users. Generally, I look at the spam that comes in to me, and I try to generalize it and create filtering rules on the mailserver that do not allow them to come to myself, or any users at all. Here is where it gets interesting, there is one domain, that literally gets hit with thousands and thousands of spams per day. They are called dictionary attacks, and the spammer will take a dictionary of common email user names, and send them out to tom@domain.com and dick@domain.com and harry@domain.com etc etc. There is not a whole lot I can do about this, aside from blocking the IP address of the sending mail server. This is pointless, becuase they use throw away dialup ISP accounts, and I can not even begin to keep up with them. Aside from that, luckily, the user of this one domain, has a less than common user name, so he is not affected. On the downside, the spammer ties up my server all day long with these attacks.
The coincidence is that the domain is very similar to yours, lets just say it has the word ‘mountain’ in it as well. So, there is something about these mountain.com domains that a group of spammers out there like for some reason or another. I have managed to track it here and there, and it seems this is a sophistaicated network that is used for this, but, after a little research, I can tell you that in my case, the senders are in China. You may have read rescently that many USA based ISP’s are simply blocking china from being able to send email to any US servers at all. I am about to do the same, just block the whole subnet of china and be done with it.
So there is the background on the matter. A few bits of advice, in the future, you can not waste your time notifying yahoo or any ISP about the matter, as the spammer has come and gone and you are merely wasting your time. Next, if you are going to continue using the domain for email, I would suggst you not use a email address that is so common, change it to firstname.lastname@mountain.com, or something that is a little less accidental to be used. As far as complaining to the website that was ‘spamvertised’, that depends, if you desire to spend a few hours getting transfered around on a phone talking to people who have no idea what email even is, then go for it, be a nice guy. More than likely, they do not know they did anything wrong, they just hired a email marketing company and thought that it was a ok thing to be doing. I am more than certain that they have gottne enough complaints by now that if there is any chance they will stop, they will. And finally, I would not reply to any of the people that asked you to remove them from the email list. Some will take any further contact as yet another unsolited email, and this time, it coming from you for real, would report you to their ISP, and you may have to deal with the repercussions. So, in short, ignore it all, it should pass in time, and change your email address, and you should be good to go.