I have a formula field that combines 2 separate lookup fields with email addresses together.

When I use the formula field that combines all email addresses as my email recipients in the Sendgrid APP, instead of sending a single email to all the recipients, it sends emails to each individual separately. How can I structure the field so that a single email is sent to all recipients?

Formula used in the combined field:

IF({Field 1}=BLANK(), {Field 2}, IF({Field 2}=BLANK(),{Field 1},{Field 1} & ", " & {Field 2}))