People the post here are most likely from Kerio STAFF. This is maybe the worst mail server out there.I have tired them all. ALL. Tenon blows this away! Tech support is awesome at Tenon as well. Have a look at the homepage. Try calling for tech support! This COMPANY IS A PC company! They are rude and have no interest in helping MAC clients. I went ahead and tried the software now for about 2 weeks on and off. Just to be fair and give it a chance. What a joke, Crashed my system, changed permissions on other disks, Then tried to get tech support. Good Luck. Worst company in the world for tech support. Very non helpful staff, most of them that I spoke with in the course of 1 day were RUDE, and made it seem like I was wrong for asking questions. The interface is that of a PC. UGLE! It is soooooooo Slow! And take a lot of processor power! if you like to be treated like sh*t buy this. If you like to have to reinstall your hole system , Buy this. If you like having apps crash after installing this. Buy this. My option Junk, Should not be sold to mac users!