Mails poste

You're referring to the postal service!

In French, the correct phrase is "envois postaux" or simply "poste". Here are a few more phrases related to the postal service:

• Envoyer par poste (to send by mail)
• Recevoir un courrier (to receive a letter)
• Envoyer un colis (to send a package)
• La poste (the post office)
• Bureau de poste (post office)
• Timbre-poste (stamp)
• Envoi gratuit (free shipping)

I hope that helps!