In PipeMail, everything about email is as close to reality as possible. Just like sending mail in real life, in PipeMail, your mail must be stamped. What is the Stamp? The NFT! Any NFT, both ERC721 and ERC1155, can be used as stamps.Attention:Although PipeMail supports ERC721 and ERC1155 NFTs as stamps, there are still limitations:ERC721: PipeMail supports all ERC721 NFTs without any limitations.ERC1155: Limitations vary by publisher.Published by PipeMail: No limitations.Published by others: ...