I would be very careful doing this and only send to those who you know won't mind. If one or more people report it as unsolicited PM spam you run the risk of a ban so I'd take that into consideration.
So you can get banned for sending an unsolicited PM? That is really shocking. Anyhow, it is pretty easy to send a message to more than one member of this forum, just simply type in the members' usernames, in the Bcc box, and make sure to space the names out with a comma.
Sending unsolicited PMs is considered spamming and will get your bitcointalk account banned.
Mass sending them is a clear ticket to a permanent ban.