White mail post

You're referring to a "white mail post"!

A white mail post is a type of postal service where the sender's return address is not printed on the envelope, but instead, the recipient's address is printed in white ink on a white envelope. This type of post is often used for formal or official correspondence, such as business letters, invoices, or formal invitations.

The term "white mail" comes from the fact that the recipient's address is printed in white ink on a white envelope, making it stand out against the background. This type of post is also sometimes referred to as "white envelope mail" or "white label mail".

White mail posts are often used for formal or professional correspondence because they convey a sense of elegance and sophistication. They are also often used for important or official documents, such as legal documents, contracts, or formal notifications.

In some countries, white mail posts are also used for special occasions, such as weddings, anniversaries, or birthdays. In these cases, the white envelope is often decorated with a special design or motif to make it more festive and celebratory.

Overall, white mail posts are a unique and distinctive way to send mail, and they can add a touch of elegance and sophistication to any correspondence.