I have 2007 still on dozens of systems. It's 100% compatible, SMTP hasn't changed. Make sure you have the option in account settings, more settings, "My outgoing server requires authentication". This prevents your server from being an open relay.
Yep you are correct. I just set an account up on outlook 2007 and seems like mine works ok. My vps must have been corrected.
I referred someone to KH and the person bought a VPS and now cannot use outlook 2007. Contacted KH support and after a while told him sorry but he would have to get the new outlook . The new client's VPS account may still not have been adjusted on the TLS versions.
@KH-JonathanKW Good to know, thanks. The "None" option for the encryption setting will always work until cPanel forces the use of TLS. As long as they don't require HIPAA compliance and packet sniffers aren't a concern then that option is always an option.