How can I email more than 100 people at once for an event w/o being spam filtered?

feld-a-mundo asked: I am organizing my high school reunion and have email addresses for 120 members of our class. I want to send them announcements using BCC (as some members want to remain private) but I’m worried about ISPs confusing my message for spam. Any suggestions? One person recommends breaking the list up in chunks, [...]