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Hi everybody,
I have SQL Server with Database mail sending emails by Office 365 administered by client.
SQL is configured to use SSL, smtp.office365.com and port 587, account name and correct password.
It was working perfect, but few days ago sending stopped. I investigate that now smtp.office365.com needs STARTTLS command do relay mails.
What have to be done on Office365 connecor or what you suggest to chage on SQL Server database mail to allow use Office365?
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Most likely this is due to the new TLS 1.2 requirement in office365.com being turned on for your account.
Please see:
https://learn.microsoft.com/en-us/microsoft-365/compliance/prepare-tls-1.2-in-office-365?view=o365-worldwide
I think it's not a TLS 1.2 problem (I can send mails using email application with STARTTLS options from this server, but it not works with TLS, as in SQL is possible to configure - ony one allowed option). I tried using email application with test server with TLS 1.2 as only possible protocol- the same results. I suppose, settings on Office365 was changed, but I can't confirm that and I'm not familiar with Office365 administration.
What version of SQL Server are you using?
There are issues with supporting TLS 1.2 when using eg SQL Server 2016 (based on the .NET build runtime version)
SQL 2017, but it appears with email clients like ThunderBird: STARTTLS works, TLS not (the same settings as Database mail).
It is how SQL Server handles mails... it uses System.Net.Mail for mailing... which means it relies on the installed .Net version and how that one uses TLS (enabled/disabled)
There is an update for TLS1.2 and SQL Server... maybe that one helps
https://support.microsoft.com/en-us/topic/kb3135244-tls-1-2-support-for-microsoft-sql-server-e4472ef8-90a9-13c1-e4d8-44aad198cdbe
otherwise from my understanding,
make sure you're using the correct -Net version which supports TLS1.2 (and also it is necessary to deactivate all other TLS versions other than TLS1.2 in order to force SQL Server to use 1.2.
Therefore the recommendation is to change some registry keys
Hi @Krzysztof Cybula ,
Did you check the "This server requires a secure connection (SSL)" option during configure DB mail? This must be ticked to enable the STARTTLS command that establishes a secure communications channel over which SMTP Basic authentication gets sent. Please check the detail suggestion information from this old thread.
Please also check if below blog could help you.
SQL Server Database Mail Failure Troubleshooting & Two Common Issues
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Yes, SSL checkbox was ON.
As I wrote, it worked for few days ago. Tests on Thunderbird shows, that Office365 requires STARTTLS command, not suppot full TLS connection. IMO problem is with Office365 Microsoft Security Defaults - but I can't test it (no permission), here are details in situatikon like my:
https://www.jeeja.biz/2021/07/01/sql-server-why-your-database-mail-is-not-working-and-probably-never-will