Email, which is one of the oldest services available on the internet, is a key mechanism via which you can reach out to your users. Over the last year, the number of services providing this infrastructure as a service has grown to include 6 email sending APIs. The newest, Amazon Simple Email Service, validates the market.
SendGrid announced they are sunsetting two of their API endpoints this month. In an email sent to their API consumers, Sendgrid stated that all API calls must now use a new base URL. They also directed developers to reference SendGrid’s API documentation or contact them through their attached email.
Additional third party integration with Gmail has been possible (you only have to look at all the contact import features from sites like Facebook), but these have either been clunky manual procedures that involve exporting contacts to a CVS file, or they require you to supply your email password. Neither option is all that attractive. Now there is an alternative. Google have recently added the ability to access the IMAP/SMTP features of particular Gmail account using OAuth.