Sending email to 365 server

[rlebeau]

On which line of code does the error happen on?
[ZSL] error at "idSMTP1.Connect;"

What does the call stack look like when the error happens?
[ZSL] Callstack:
main thread ($30ac):
0068b8cb +073 Prj2.exe    IdStack                        929  +54 TIdStack.RaiseSocketError
0068b852 +016 Prj2.exe    IdStack                        852  +1 TIdStack.RaiseLastSocketError
0068b7bd +015 Prj2.exe    IdStack                        826  +2 TIdStack.CheckForSocketError
006879b4 +0b0 Prj2.exe    IdStackWindows                2026  +20 TIdStackWindows.Connect
<snip>

That trace means that Indy is attempting a direct TCP connection to the specified Host/Port, so a timeout on that operation at the OS layer means that either:

• you don't have a viable network router to that Host (or to a DNS server that can resolve that Host name to an IP). Can you ping the server?
  
• you are not actually connecting to the correct Host/Port to begin with (which goes back to my suggestion to verify that with a sniffer).
  
• the TCP handshake is getting lost and not being completed (which a sniffer will also see).
  

How long does it take to time out?  TIdSSLIOHandlerSocketOpenSSL does use a 30 second timeout on Windows Vista+ if its ReadTimeout property is <= 0 (which it is by default).
[ZSL] after about 30 seconds

The timeout in question that TIdSSLIOHandlerSocketOpenSSL uses internally only applies after the TCP connection has been established and the SSL/TLS handshake is in progress. You are not even getting that far, there is no TCP connection being established.