I'll take the opportunity to be the 25th review for MailMeteor ;-)

This truly is an AWESOME product for anyone who lives in Google Sheets like I do -- it really helps keep small prospecting or 1-off group emailing efforts super organized and efficient. I don't use it as my main email tool (I use SalesLoft, Acumbamail, and Instantly), but MailMeteor is the PERFECT additional tool in the toolbox to shoot out any short-term or batch type of email outreach. 5 tacos all the way!