# T.37

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This article is about the communications standard. For other uses, see [T37 (disambiguation)](/source/T37_(disambiguation)).

**T.37** is an [ITU](/source/ITU) standard which deals with sending [fax](/source/Fax) messages using email. It is also referred to as "Internet fax" or "Store-forward-fax".

A fax machine supporting T.37 will send a fax to an email address by converting the document to a [TIFF-F](/source/TIFF) image, attaching it to an email (using the [MIME](/source/MIME) format), and sending the document (using [SMTP](/source/SMTP)). The destination fax receives the email and prints the attached document.

To interface with regular fax machines:

- T.37 can be used in conjunction with [fax gateways](/source/Fax_server) to communicate with regular fax machines. The fax gateway converts emails to regular faxes or regular faxes to emails.
- A T.37-compliant fax machine includes legacy fax functionality to send to regular fax numbers and requires a phone line for this.
- To find the destination faxes email address, the RFC 4143 standard is in development, which allows a fax machine to use a destination fax number to look up an alternative email address.

## See also

- [Unified messaging](/source/Unified_messaging)
- [T.38](/source/T.38) (Fax over the Internet Protocol)
- [Internet fax](/source/Internet_fax)

## External links

- [Official ITU-T T.37 page](https://www.itu.int/rec/T-REC-T.37/en)
- [Cisco Fax over IP T.37 Store and Forward Fax](https://www.cisco.com/en/US/tech/tk652/tk777/technologies_white_paper09186a00801fe5da.shtml)

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Adapted from the Wikipedia article [T.37](https://en.wikipedia.org/wiki/T.37) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/T.37?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.