Encrypt outbound faxes

InterFAX is a secure fax-to-email service that supports SSL access, strong encryption and HIPAA compliance. This page explains how to enable encryption for outbound faxes.

For more information on encrypting inbound fax messages or fax confirmations, see Encrypt inbound faxes and Encrypt 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 transmitted from your computer to our servers.

Developers please note: When faxing through the InterFAX XML Web Service, you may use SSL 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.
  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. Log in to your account,
  2. Navigate to My Settings / Outgoing Options / Fax Operations.
  3. Under the Encrypting emails to InterFAX section, click Retrieve certificate.
  4. A popup screen will allow you to add email addresses to which a digitally signed email will be sent (you may enter multiple, comma-separated addresses).
  5. You will receive a signed email fromInterFAX.
  6. Add the sender to your address book (e.g. in Outlook Express, right-click the sender name and select Add to Address Book).
  7. Verify that the address book entry includes a digital ID.

Note: This process will only need to be performed once, so long as 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 (e.g. This is a test message /fax=+12125551212).

    Multiple recipients may be entered by separating them with semicolons (e.g. /fax=faxnumber1;faxnumber2;faxnumber3).

  3. Click the Encrypt link within your email program to send an encrypted message.

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

You may wish to further encrypt your message and hide the destination fax number, by following these instructions;

In the subject line add /fax=body, using the literal term test here ‘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 addresses, separate the numbers with semicolons (e.g. !*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).