We have been seeing a lot of reports lately of issues with alert, FAX, and VM emails not being able to send properly using SMTP via postfix with certain 3rd party relays like GMail/GSuite, Office365, 1and1, etc. This guide is intended to help you address some of these issue and get emails sending properly. You can quickly see that messages are failing if you see a 🔥 icon next to the Mail Queue item on the Dashboard. Upon hovering your mouse pointer over the 🔥 icon, you are informed that there are undelivered messages in queue:
NOTE: If the message you see upon hovering your pointer is instead a message stating that the service is not running, can't be started, or the status is unknown, you are likely instead suffering from the postfix permissions bug. You can remedy this by running:
Running this will have no ill effects on your instance, even if you aren't suffering postfix service runtime issues. So, running this is a safe first troubleshooting step. Then proceed to the specific cases below.
Pain Point 1 : Large volumes of emails via GMail/GSuite
The default GMail/GSuite SMTP server utilized by the handy GMail provider button in the System Admin > Email Setup page is the standard low-volume server that only allows up to 2000 emails sent per 24 hour period per GMail/GSuite account (NOT ALIAS). If you are using GSuite and are expecting your sent email volume to exceed 2000 messages per day, you will need to utilize the Other provider, manually specify smtp-relay.gmail.com, Use Authentication, Use TLS, & Require Both SASL options. You may need to alter your GSuite permissions to allow use of the high-volume relay.