Where to set reply-to in send email smart service?
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This node does not support that.
However, note if you use "Custom Sender" as the From, the email will be sent "on behalf of" that email address, and anytime a recipient hits Reply, it will pull in that custom email address to reply to, vs the system email address.
It is very much possible. look at the following.
Here is the actual email.
When user hits reply to original email the Sender Email mentioned in the email configuration node will be used.