Site Settings/Difference between 'From' ~ 'Reply-To' ~ 'Notification Email'

I’ve searched regarding this on meta, but couldn’t know.

I only know the 1 ‘From’ setting that can be configured in my ‘Site Settings’. ‘From’ and The email receiver sees 4 fields (shown in my screen shot). Which of these can be configured in our site settings (and where) and which can be set thru Amazon SES (or MailGun).

These are:

  • From:
  • Reply-To:
  • Mailed-By:
  • Signed-By:

Also, does ‘Reply-By’ setting in the site settings has any effect on any of these 4 given/asked above?