Pretty much every email platforms allows me to send out a test message to one person or a list of people (via check boxes).

Backstory:

I kept sending out a "test text to myself" to myself and a team lead. once it got approved, didn't want to retype the message so i copied and pasted it from my phone and forgot to update the merge tag back from David to {{Merge Tag First Name}}... and 2,500 people got a text saying "HEY DAVID,...." tragic day.