Do you have a mailing list set up, and you use that by mistake? Have you checked for malware?

smagann said

I forwarded an email to my husband but the email went to about 15 people who were not supposed to receive it. These people are in my address book but not on a list to receive emails and it appears that the service picked them randomly. Not good!!

I ran spy bot and found no problems. I do have several lists but those receiving the email were random...none of them were on the same list.

The message you forwarded was that sent to a list? And did you reply to the list, its easy just above forward? could be an easy mistake. Just check it. please