We love filing letters of protest. The Cohen IP Law Group frequently uses this lesser known trademark procedure prior to the publication period to oppose a pending trademark application that my go to issuance without having to file an actual opposition proceeding. So what is a Letter or Protest? Essentially it allows a third party to bring forth evidence ex parte that was not known to the examining attorney assigned to a particular trademark application, to let him become aware that the pending application he is reviewing should not be issued. The Letter of Protest must be filed before Publication, although in some cases you may be able to submit after publication, but it is much more difficult, and typically you would need to file an Opposition by that time.
The beauty of the Letter of Protest is that if your evidence and reasoning is convincing, the examining attorney could base an Office Action (rejection) on it that he initially would not have. As a result, time and money is saved by avoiding a tougher Opposition or Cancellation filing.