So...... I have a number of SQL servers a few of which are set to send emails to certain accounts based on their results (failures mostly). This has worked for years but now I have ceveral systems that don't fully work.
I have a 2016 SQL RTM (with current SP) running on Win 2016 (fully patched). SQL mail has been configured and was working for addresses internal and external but now externals are failing.
Successful test include: test emails from SSMS Database Mail icon and from a SQL script. Using internal email addresses only.
Failures: test emails from SSMS Database Mail icon going to firstname.lastname@example.org (or net) or to my gmail account. The interesting thing is that the script will send successful email to my cell phone but not gmail. The other thing I tested was sending directly from my local email client and both cell and gmail worked. This tells me that the server is allowing the traffic.
Am I going crazy or have I missed something or was there an update that caused this to start acting this way. I didn't want to write a novel on this so please let me know what else I need to provide for assistance.