We have a smtp and pop sensor that has worked for more than one year without much problems. Yesterday it stopped to work suddenly, while normal mail is still flowing. Looking at the SMTP dialog with Wireshark, I noticed in the client hello packet that the TLS level choosen by the Prtg server is SSL3, just before being dumped without more ado by the mail provider server (no server hello). I can't fault our mail provider for rejecting this quite outdated protocol. Is there a way to select TLS 1.2 instead ? that's what our normal mail software use to connect to the mail provider.
This is with Prtg 188.8.131.527
C:\>"C:\Program Files (x86)\PRTG Network Monitor\openssl.exe" version OpenSSL 1.0.1g 7 Apr 2014 (Library: OpenSSL 1.0.2k 26 Jan 2017)