WAA Version: 4.3.X

OS: Linux and Windows

Q1: How can I configure multiple SMTP servers to WAA with WAC? 
Answer: You can only set one SMTP. 


Q2: How to specify the listening port number of the SMTP 
server other than the default 25. 
Answer:
- Unchecked with "With Authentication":use port number of 25 
- Checked with "With Authentication":use port number of 587 
- These numbers are fixed. It can not be changed.

More information: N/A