Amazon SES
Email with Amazon SES
Invitations and reminders are sent through Amazon SES, which reports back on delivery.
Emails wait in a queue and are sent through Amazon SES. A failed send is retried with growing delays, from 30 seconds up to 6 hours.
SES reports each email’s fate (delivered, bounced or complained) through a signed notification, and the result shows up in the request’s email history.