Time to Switch from SMTP Communication Transports Published May 23, 2022 The communication transport you use in Rock is important. In the old days, emails had to be delivered from Rock using an older technology called SMTP. In Rock v8, we delivered a higher performance option that runs on HTTPS. It’s important that you switch to these newer transports not only for the speed boost, but also because the older transports are being removed. Recent multi-threading improvements in how Rock sends communications have significantly boosted the speed at which messages to a large number of recipients can be sent. The continued use of the SMTP transport, however, works against these performance improvements and has created some reported issues with randomly corrupted attachments. The good news is that moving to the more robust HTTP transports is very easy. These newer transports have been available for both MailGun and Twilio SendGrid for many years. Please see our documentation on Email Integrations for help. These options will be removed from Rock in version v14. We’ll also be removing support for Mandrill SMTP at that time since this service is no longer actively available outside of Mailchimp.