o365 SMTP relay no longer working

[Rundc]

Hey,

 

I've recently inherited a Microsoft school, generally I've been working with google schools and not had much experience in the o365 enviroment.

 

Anyway it looks like SMTP relay is failing for this school, doing some digging it looks to have started recently after a new SSL certificate was insatlled, when testing the connector thats configured for this I receive a message along the lines of "450 4.4.317 Cannot connect to remote server [Message=451 5.7.3 STARTTLS is required to send mail]"

 

Am I right in thinking the new SSL cert is the cause of this and if so how do I rectify it?

Edited August 23, 2023 by Rundc

[MikeW]

This article outlines what needs to be done after a new certificate has been installed.

[Rundc]

This article outlines what needs to be done after a new certificate has been installed.

 

Thanks, I had found thisd article but couldn't find the cert....

 

Found the cert and will install and test.... fingers crossed!

Edited August 23, 2023 by Rundc

[Rundc]

I've been through the article, but SMTP relay still not working...

 

I was receiving Event ID's 12014 MSExchangeFrontEndTransport before insatlling the cert and running the hybrid configuration wizard and now i'm getting 12023 which references an old cert

 

Can anyone help?

Edited August 23, 2023 by Rundc