I would also add security as one benefit. Not sure how others feel, but I think Gmail is one of the most secure ways for me to handle my email (US government ag

I would also add security as one benefit. Not sure how others feel, but I think Gmail is one of the most secure ways for me to handle my email (US government agencies are not on my threat list). I think Google takes security very seriously and their scale allows them to do and know things smaller vendors would not know. While rolling your own email server is fairly easy thing to do, you can easily open attack vectors you don't think about. Like social engineering attacks against your hosting or DNS provider which would allow attacker to get control of your server or traffic. These kind of tricks can be pulled of by people who just get annoyed on you on Internet or who want to take your nice Twitter handle.