> Perhaps delivered eventually (delayed). This is how email is designed. Mail servers will continue to try to deliver for quite some time before giving up. T

> Perhaps delivered eventually (delayed). This is how email is designed. Mail servers will continue to try to deliver for quite some time before giving up. The email transmission protocol was designed way back in the day of intermittent internet connections, so it has already backed into its design the concept of retry some number of times before giving up. FWIW, twitter uses google as their email: twitter.com mail exchanger = 30 ASPMX3.GOOGLEMAIL.com. twitter.com mail exchanger = 20 alt2.aspmx.l.google.com. twitter.com mail exchanger = 30 ASPMX2.GOOGLEMAIL.com. twitter.com mail exchanger = 20 alt1.aspmx.l.google.com. twitter.com mail exchanger = 10 aspmx.l.google.com. So anyone who had twitter's MX records cached in their local DNS servers would never have noticed a problem from the dyn outage (as least not until the cache expired).