said by TomS_:
So my suggestion is: dont offer email to your customers unless they absolutely must have an email address on your domain, and if they do, charge for it.
I'll second this. The only reason I run an email server is because I started doing web hosting BEFORE starting my WISP, so I essentially had free web hosting and email for my new business venture. But supporting email can quickly become more of a burden than it is worth. I can't tell you how many "how do I set up my email address on my new windows 8/android, IOS, blah blah blah device I got for christmas" calls I've gotten in the last few weeks. And dealing with constant spam isn't worth it.
I'm not against offering email accounts to customers because it can be convenient for those who are technically challenged (plus it helps keep a customer if they don't want to go through the pain of switching email accounts, but I don't really want THAT to be the reason they choose to be my customer). If you choose a good web hosting (I wouldn't consider godaddy.com to be very good) and they offer good spam filtering and a nice webmail platform, email can be a nice bonus, but as mentioned, free email accounts are really the standard today and out of about 250 accounts, I've only had maybe 50 sign up for addresses, and most of those were 3+ years ago. I rarely have someone choosing to sign up for an email account through my domain anymore, and that's fine with me.