The tool has been very helpful in my work as I use it daily for both sending out emails internally within our team but also externally from time to time when needed.
At times there can be issues where you have not set up an auto responder that works (or sometimes just no reply at all). If this happens then simply send another email asking if anyone received yours or ask someone else who may know about how things are working etc! There aren't many downsides other than some minor bugs here/there which don’t really bother me too much. When using we find ourselves being able to get more replies back quicker so less people miss messages because their inbox was full / busy at certain points during office working days / weekends etc..