Enabling Encryption for Outbound Faxes

InterFAX is a secure email-to-fax service, supporting TLS access, strong encryption and HIPAA compliance. For an introduction to InterFAX's encryption features, see our encrypted fax solution page.

This page explains how to enable encryption for outbound faxes. See also our documentation on enabling encryption for inbound fax messages and encryption for fax confirmations.

Enabling Encryption for Outbound Fax Messages

The security of messages sent through the InterFAX system may be enhanced by encrypting your emails. While this will NOT encrypt the fax transmission from our servers to the fax machine itself, it WILL secure the contents of your message while it is in transit from your computer to our servers.

(Developers please note: When faxing through the InterFAX XML Web Service, you may use TLS to access our servers securely at https://ws.interfax.net)

There are two steps to encrypting fax messages sent to InterFAX:

  1. Obtaining the InterFAX public key signature, and
  2. Encrypting your messages.

Obtain the InterFAX public key 'signature'

This step only needs to be done once, or whenever your keys are renewed.

  1. Login to your account, then select Preferences -> Outgoing. Under the 'Authentication and Feedback' section find the paragraph titled 'Encrypting emails to InterFAX'. Click the 'Click Here' link.
  2. A popup screen will allow you to feed in the email address(es) to which a digitally signed email will be sent.  You may enter multiple, comma-separated addresses.
  3. You will receive a signed email from InterFAX. Add the sender to your address book (e.g., in Outlook Express, right-click the sender name and select 'Add to Address Book'). Verify that the address book entry includes a digital ID.

Note that this process needs to be performed only once, if you retain the InterFAX digital ID in your address book.

Encrypt Your Message

When sending emails to be converted to faxes:

  1. Address the message to the newly-created address book entry, send@fax.tc (and not to the usual faxnumber@fax.tc).
  2. In your email's subject line add /fax=faxnumber, where faxnumber is the destination number, as usual (e.g. This is a test message /fax=+12125551212).  Multiple recipients may be entered by separating them with semicolons (;), like this: /fax=faxnumber1;faxnumber2;faxnumber3
  3. Click the "Encrypt" button on your email program to send the message encrypted.

If you wish to obtain a security certificate to sign your emails, you can obtain one at the Thawte web site for free.

Encrypt Your Message Even Further

The solution above leaves the destination fax number "in the clear". You may wish to further encrypt your message and hide the destination fax number. Here's how to do it.

In the subject line add /fax=body, using the literal term "body" instead of the fax number indicated in the preceding section. Then, enter !*faxnumber*! (exclamation mark, star, destination fax number, star exclamation mark) anywhere in the email's body.

For multiple recipient addresses separate the numbers with semicolons (;), like this: !*faxnumber1*!;!*faxnumber2*!;!*faxnumber3*!.

To broadcast the fax to a list of recipients managed through InterFAX's online list management screens, enter !*list=listname*! (exclamation mark, star, the word "list", equals sign, name of the list you wish to fax to, star, exclamation mark).

Related Articles

Receive encrypted confirmations of sent faxes
Fax encryption - secure inbound fax messages with Interfax fax to email service

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