We are running Exchange Server 2003 SP2 on Server 2003. Webmail (http://yourdomain.com/exchange) is working from the internal network but not from outside the network. When trying to access it from outside it returns a Timed Out error.
This video shows how to quickly and easily add an email signature for all users on Exchange 2016. The resulting signature is applied on a server level by Exchange Online.
The email signature template has been downloaded from: