said by OZO:Depends on how paranoid you are I suppose.
You may create "personal" account for any service (or a person), that asks your mail address. Then, if they start to spam you (or sell your address to other spamers), it's easy to block only them. That's exactly how I manage accounts in my personal mail server. And BTW, if you use your own mail server, when online store sends a confirmation mail, containing your address, last 4 digits of CC you used to make purchase, price, product name, merchant name, etc. to your account, it goes directly to you and is not stored in Gmail or Yahoo or other similar provider, that like to analyze and store them for their own use. It simply comes directly to you. There is no MITM, that always wants to watch you.
So, running your own mail server brings a lot of benefits, protects your privacy and dramatically reduces spam that you may get.