We have several tutorials to help you get started as well as how to use advanced features:
Absolutely. Each campaign that you send will add a "merge status" column within the sheet. So you can send as many campaigns to the same contacts list (or segment your sheet). Pro tip: flip through the tracking report to watch which campaign ranks the best.
If you have enabled alias within your Gmail account, you can send emails from it in Mailmeteor. To learn more about how to do it, follow the "Send from an alias" guide.
Here a quick list of the top features that Mailmeteor provides:
If you are looking for more features, have a look at this section.