When you send a postcard, you are sending an email, not a letter.
post | title Postcard sending and receiving requires that the postcard has a clear signature from the sender.
If the post card is unsigned, the sender can’t use the postal service’s signature.
In addition, postcards sent by post offices with invalid signatures have a high probability of being lost or destroyed by the post office.
The postal service does not require that a post card include a signature on the back, but it does require that the recipient sign the back of the postcards.
However, post cards sent by the USPS can be opened by anyone without the signature of the sender, and it is easy for anyone to open postcards for the sender without signing them.
To open a postcards, you need to have a valid USPS account.
If you do not have a USPS account, you can create one by going to https://accounts.usps.com/customer/service/create-a-postcard-service.php?userid=12345678 and filling out the information.
After filling out this form, the USPS will send you a new address for your new USPS account to send postcards to.
It is recommended that you use the same email address for both your new and existing USPS accounts.
If you do decide to change your email address, you will need to log in to your old account every time you want to send a mail to your new account.