After getting the email and downloading attachments:
For Each %CurrentItem% in %RetrievedEmails%
Parse Text %CurrentItem.From% to find "@" as %Position% 'note: this is the wrong format; when you set it up, use the dropdowns...it's something like %CurrentItem['From']; not sure why...to and from email properties are the only ones like this. Parse text gives you the position of the text you are looking to find.
Parse Text %CurrentItem.From% to find ".com" as %Position2%
Get SubText %CurrentItem.From% from %Position + 1% to %Position2 - 1% 'I may be wrong on Position 2 - 1, just change it to -2 or just %Position2%....little trial and error.
Rename Files %CurrentItem.Attachment% to 'whatever format you want to name it to using the domain you've extracted
Move Files %RenamedFiles% to whatever folder you want so it's not in your downloads folder.
End (For Each)
This will loop through all emails, rename attachments based on the domain of the From email, and move it to the folder of your preference.
Good luck!