Merge email field from a different row

I created a task that sends an email to a contact when the row is updated. Is there a way to included a merge field in the body of the email that pulls data from a different row that I specify?

Specify how?

@Steve that would be a second part of my question. But I was thinking somewhere along the lines of using the Lookup() function or anything out there that might work?
Thanks.

If you’re using a template to produce the email content, you cam include any app data.

See also: