I once used Yahoo mail as my primary email. Then I discovered if I didn't log in for 3 months, they deleted all my mails! Needless to say, I switch to Gmail very quickly. The latest is that Yahoo have made a decision to drop all "unused" email accounts to allow new people to register with those accounts again.
Well, what if I don't want my accounts that I haven't used for 2 years to be stolen? What if I had sensitive data still coming in? Emails are also used for a lot of account verification for a lot of services and websites, so where does all that security go? I don't care if I haven't accessed my mail account in 3 days, 6 months, or 13 years. I expect my old mails to still be there or I *WILL* go elsewhere.
I will never support Yahoo again. That company needs to die in a fire.