In general I wouldn't have a problem with it on that site using the on-site e-mail. However, I believe I got the same message as you did and it seems like if you want to drum up business, you should message people earlier than the day of your visit.
I get notices of traveling companions all the time and that is fine by me since I'd like to see what my options are when I get the urge. I also don't mind getting PM's about availability from providers from time to time.
PM's are one thing...and cool. Getting phone calls or text messages are definately NOT cool. I used to get text messages all the time that said something to the effect of "Hey baby, thinking about you...i'm running a special so call me". I'm single and use a ho phone so it wasn't a big deal, but that could cause lots of trouble for some other guys.
I am not going to lie, sometimes while I travel I send messages through e.com. But mainly to clients that I have seen before who have written reviews. But hey once in a while you need to spice things up with something new so I'll send out a message to a few men that have a good reputation in the hobby. This is due to the fact that I am no longer really newbie friendly. Unless your new to chocolate!