Mass Email Christmas Greetings without spamming

The person who sends out our company holiday greetings no longer works for us and its fallen to me to send out an ecard I created in Photoshop.  I'm IT support so this isn't my fortee but I want to be sure I don't get nailed as a spammer.  I was told I can send to 10-20 people at a time and be safe, does this apply to mail merge?  Is there a way to make the process easier, like create and save a draft and open and send it (ok this might be mail merge but I've no real experience with utilizing this feature in a workplace)?  

Also we don't really have a up-to-date contact list, that anyone can find, so I copied the emails from the messages sent last year.  This poses a problem with new contacts.  Is there a way to check or track who I've mailed to with a massive master list?

Any help is greatly appreciated!