It's probably correct yes.
I had some troubles too to set up AutoMailUploaderService recently and finally got it. The only difference is that I was not using impersonate user.
Now we have migrate on cloud (Office 365) and we are using port 993 with TLS1_2 Implicit and it works fine.
I had the case on a customer and I simply disabled the SSL and for mysterious reason, it works without it.