Portugal has a national postal service, known as CTT, with locations throughout the country, especially in major urban centers. You can find red mailboxes to drop off your correspondence. Stamps can be purchased at any CTT counter, as well as at newsstands or small shops offering basic postal services. Portuguese stamps can also be bought online on the CTT website.
When sending a letter to Portugal, you will need to know the postal code of the address. Portuguese postal codes have seven digits. To find a CTT Post Office or a mailbox, see:
https://www.ctt.pt/feapl_2/app/open/stationSearch/stationSearch.jspx?lang=01#stationSearchPanel
