Mail real paper letters (standard, registered, registered with receipt) worldwide. No account.
Free
One server, in communication & collaboration. Mail real paper letters (standard, registered, registered with receipt) worldwide. No account.
Communication & Collaboration
Mail real paper letters (standard, registered, registered with receipt) worldwide. No account.
The rest either hold an API key issued by the publisher or ask for nothing.
Listed without a verification tick. Read the listing before installing.