Best Free email service?

When is the best timing to request email addresses of users when they sign up to our web service using Twitter OAuth?

• Some services such as let people sign up to their services using Twitter authentication method. The benefit for this part is pretty clear in that it lets people try a service without going through tedious process of signing up, as well as discovering other friends who are using the site, which translates to higher engagement. However, if it's just Twitter sign in, there is no way to bring users back to the site via email. If we don't have user's email address, it is not easy to send them notifications about any event that may bring them back to the site. We are working on a web service and want to use Twitter Oauth as a signup method. When is the best timing to receive emails? Some services seem to force email addresses before trying the service, and some seem to make it optional so people can add it later. What are your experiences with this? Any insight? Thanks!

• Answer:

  Allowing twitter signups allows anyone to use your service fairly quickly.  If email address is critical to usage - ask for it immediately after signup. Plancast hardly sends any email to users. So it can do without email addresses.