An ITU-T Recommendation issued in June 1998 for Fax over Internet Protocol (FoIP) in storeand-forward mode via e-mail, through the use of SMTP (Simple Mail Transfer Protocol) and MIME (Multipurpose Internet Mail Extensions) protocols. The ITU-T and Internet Engineering Task Force (IETF) jointly developed the standard, which the IETF mirrors in RFCs 2301-2306.T.37 specifies the attachment of fax image documents to e-mail headers and their encoding in the Tagged Image File Format-Fax (TIFF-F) data format using Modified Huffman (MH) compression. In simple-mode, T.37 uses the TIFFF S-profile and restricts fax transmission to the most popular fax machine formats (e.g., standard or fine resolution, and standard page size). Simple-mode provides no confirmation of delivery. Full-mode extensions include mechanisms for ensuring call completion through negotiation of capabilities between transmit and receive devices. Full-mode also provides for delivery confirmation. Extensions have been developed for color fax, as well as black-and-white and grayscale.