SmartReply 365 is an utility for Outlook desktop (Windows) users who have enabled the Microsoft feature to send emails from an alias in Office 365 (see https://www.derekseaman.com/2021...).
This utility will automatically populate the proper From: address when you reply to or forward a message received as an alias.
In other words, if you get a message addressed to jdoe_alias@contoso.com and hit Reply(Reply All, Forward) button, the replied/forwarded message will have jdoe_alias@contoso.com in the From: field.
In addition, SmartReply 365 can assign different signatures to different aliases.