Changing configuration of starting a process via. Email

Hi All

I am currently working on version 22.3!!

I have a use case wherein one of my current process is started when an external system sends email on the process model id i.e.: processmodel<id> here dev represents the Appian environment). The requirement is that:
The system can receive external mails using company's SMTP i.e. rather than 

Would like to know is there a way I can do this? 
I have read the the topic "Legacy configurations" in the link below but I am not able to understand what does reply-to-address means and will it even help me in my problem:

Thanks in advance!!

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