I like how easy it is to send emails to many recipients at once. It also makes scheduling meetings easier than having everyone set up their own meeting scheduler or emailing each other individually via Outlook, Google Calendar etcetera. Sometimes you can't see who has received your message until too late when they're replying to say that yes they've read them! - That's not really an issue per se but would be nice if there were some way of viewing this info more quickly as soon as someone replies saying "they have seen". Easy-to use for small teams (up to 5 people). We are using our internal mail system in order to communicate with clients about projects we manage together so can easily share documents within one inbox rather than different ones which saves time copying files around between programs/websites.