which type of email server is typically used for outgoing mail
Simple Mail Transfer Protocol SMTP communication between mail servers uses TCP port 25. Mail clients on the other hand, often submit the outgoing emails to a mail server on port 587. Despite being deprecated, mail providers sometimes still permit the use of nonstandard port 465 for this purpose.
United States Postal Service The United States Postal Service (USPS; also known as the Post Office, U.S. Mail, or Postal Service) is an independent agency of the United States federal government responsible for providing postal service in the United States, including its insular areas and associated states. It is one of the few government agencies explicitly authorized by the United States Constitution.