From Kelly Software:
GMail2 allows you to maintain your own e-mail lists and send personalized messages to your lists. You can add recipients at run time, or just load them from a text file, or both. GMail2 also has a verification feature which will verify all your e-mail addresses for you, also supports multiple attachments (Registered version only). This is great for sending personalized e-mail messages. This new version has new sorting and duplicate-removal features. You can sort the list and it will automatically remove duplicates to a dupes.txt file for you. Version 2.4 added POP-before-SMTP support, the ability to set the pause time after a defined number of e-mails, simple SMTP authentication options.