FollowUpXpert Standard 

Simple autoresponder software. No banners and no monthly fees. Use it to create both simple "I'm out of office" kind of autoresponders to ones sending series of emails to your prospects at predefined times. Can also send newsletters and bulk mail.
autoresponder autoresponders e-mail windows responder automatic responder sequential autoresponder sequential autoresponders automated email pop3

FollowUpXpert Professional 

Automate time-consuming email-related tasks you do every day! Think of it as your email assistant. It can reply to incoming emails. It can send automatic personalized follow-ups. It can send bulk mailings. It has a WYSIWYG editor. And it's very fast!
autoresponder autoresponders e-mail windows responder automatic responder sequential autoresponder sequential autoresponders automated email pop3 bulk mailer bulk newsletter