You can get a summons in the mail either by regular mail or certified mail.
You may also get a summons served in person by a sheriff or process server but most often a summons comes in mail but if you don't respond or they don't think you'll respond the summons will be served in person.
If the summons comes by certified mail you have to sign for it to be received.
I've gotten summons in regular mail before and even subpoenas as well.
The difference between a summons and a subpoena are a summons marks the beginning of a court case, a subpoena comes after a case has begun and requires the person who receives it to provide evidence that is considered important to the outcome of the case.
You can still receive a subpoena even if you aren't directly involved in the case.
A summons is a form prepared by the plaintiff and issued by a court that informs the defendant that they are being sued or are required to appear in court.
It may be served by a sheriff or other authorized person, such as the process server.
If you receive a form called a Summons (form SUM-100) it means that someone is suing you in court.
In addition to the Summons, you'll also receive another document, called a Complaint.
The Complaint says why you are being sued.
When you're summoned to come to court, that is basically your notice that a criminal case or other case has been filed against you.
And, you're usually served with a summons by a Constable or you may receive the summons in the mail, certified mail.