Comma or Colon?

[Unregistered]

My husband and I are disagreeing about this. Do you follow the salutation with a comma or with a colon in a formal letter?

Thank you

[Barb_D]

In an American letter, a colon is for formal letters and a comma for informal.

However, it may not be the case in other places.

[konungursvia]

In Canada few people would notice or care about this subtle difference, though a colon can seem curt.