After what feels like decades trying to get postfix to work on Mattermost install, I’ve given up and decided to try SendGrid as an SMTP email provider. When I set the connection security to STARTLS I get the following error: “Connection unsuccessful: Connection unsuccessful: failed to close connec…

turns out it wasn’t a sendgrid issue…it was a mattermost config issue. your send and reply to email address needs to be set to your sendgrid sender address. Somewhat counter intuitive as that content is the the notificaitons section of the system console, not the SMTP section. I ended up setting …

Mattermost + Sendgrid = Dear God, What am I Doing Wrong?

Troubleshooting

XxLilBoPeepsxX June 21, 2021, 1:03pm 4

This is where you manage and add SendGrid verified senders:

Topic		Replies	Views
[SOLVED] SendMail: Error setting "From Address", 550 SMTP Envelope Sender must be valid Troubleshooting	3	3091	January 22, 2025
SendMail: Failed to open TLS connection., tls: first record does not look like a TLS handshake Troubleshooting	0	1455	February 23, 2022
SMTP not working Troubleshooting	3	3059	September 16, 2019
Setting up SMTP Troubleshooting	1	2839	July 15, 2022
E-Mail Notification. Connection unsuccessful: Troubleshooting	2	2744	October 5, 2018

Mattermost + Sendgrid = Dear God, What am I Doing Wrong?

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