There are several types of letters the USPTO sends registration applicants and registered trademark owners. One called an Office Action Letter is common.

There are two kinds of Office Action Letters. They describe non-final and final actions in the trademark process. The Non-Final Action Letter is a form of first-contact that seeks to resolve some issue concerning your application. We recommend you respond to a Non-Final Letter through your representative.

A final Office action issues when the applicant's response to the prior Office action fails to address or overcome all issues. If you receive a Final Action Letter, you can either follow the conditions in the correspondence or file an appeal with the Trademark Trial and Appeal Board. 

Several other types of Official Letters that come from USPTO include:

• Examiner's Amendment - This form of correspondence does not need a response unless an applicant disagrees with a stated position in the document. The USPTO sends you this letter because of changes or an amendment to your application.
• Priority Action - A Priority Action Letter lets you know of information about some ongoing issue with an application. You or your representative must respond to this notification within six months from the date of the letter or USPTO will abandon your application for registration. You will lose any fees paid as part of the application process.
• Suspension Letter - This letter lets you know that the USPTO has suspended your application. We recommend you contact a professional that understands the trademark registration process to provide you with counsel.
• Suspension Inquiry Letter - You might receive this letter from an examining attorney asking for information about the status of a suspended application. You or your representative need to respond to this letter. We recommend you seek assistance from an experienced trademark professional before you respond to the correspondence.