jrockfl - 2:05 am on Jan 22, 2013 (gmt 0)
I use icontact with 25K plus subscribers and we send out 3 to 5 emails per month. You will have a higher delivery rate using a 3rd party email marketing provider than sending them yourself off your mail server.
They will also maintain the un-subscribers and provide you with reporting on the bounces, opens, click throughs, etc.
If you have 12 years worth of emails, most likely there would be a good percentage of invalid email addresses and you would be paying a higher monthly fee.