The issue was wrong open SSL binaries, I had fetched direct from OPEN SSL but this is not correct for Indy.

Indy currently supports up to OpenSSL 1.0.2u, which you can get from Indy's OpenSSL-Binaries repo.

Once I fetched the correct 32bit DLLs for my application the SMTP SSL worked again. Both 32bit and 64 bit are available from the Indy OpenSSL-Binaries Repo.