I was struggling with my SQL Server 2016 database mail after installing the Free Developer edition of Sql Server 2016. My server contains Microsoft Windows Server 2012 and I enabled the SMTP server. The SMTP server (local) was working fine but database mail refuses to work!
After spending hours on checking all configurations, asking colleagues, testing the SMTP Server (works, also via SSIS ) I gave up. Till I checked my Twitter timeline and found this article.
So if you’ve gone through all the usual steps to troubleshoot Database Mail (or these steps) in SQL Server 2016 to no avail, be sure to double check that the .Net 3.5 Framework has been installed. If not, you will need to install it, then apply ALL the patches for it.
That was It! I installed the .net framework 3.5 and all my mails where send immediately.