Fax SMTP

This section provides a complete reference for developers wishing to use our fax service to send faxes automatically via SMTP.

The InterFAX fax SMTP service enables initiation of fax transmissions using SMTP, from email-enabled environments, without the need to install any hardware or software. Developers can use our fax SMTP service to send plain text messages and messages with attachments of various formats, such as HTML, Microsoft Word, PDF etc.

After initiating a fax transmission, status information regarding individual faxes sent can be obtained by a variety of means: by a return confirmation email, by querying the service through the InterFAX Web Service or by viewing the outbound fax queue through web-based user administration screens.

Requirements | Basic usage | Advanced usage | Getting status | Usage examples | Destination number notation rules | Error conditions

Requirements

In order for you to fax using SMTP with Interfax you must have: Email access over SMTP port 25.

Basic usage

This section explains the basic usage of our fax SMTP gateway for automatic faxing.

The minimal requirement for initiating a fax is sending an email with the following parameters. The resulting fax will be a plain-text document whose content is the email body.

Optional fields

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Advanced usage

This section explains how to perform advanced operations when sending faxes using our fax SMTP.

Advanced modifiers

Subject line modifiers | Sending attachments | Password authentication

Subject line modifiers

The following modifiers may be added to the end of the email’s Subject line to modify InterFAX’s behavior.

Note: Modifiers may be combined like:[Subject] /b /d 2002-01-01 18:01 /rs /Legal

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Sending attachments

Several document attachments may be faxed in one message. The following table lists the resulting output, depending on usage of the /b and /bn modifiers.

See Supported file types for information about supported attachment types.

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Password authentication

Users who wish to apply an additional level of security to their faxing may elect to send their password with each outgoing email. This will offer another layer of identification in addition to the standard From header used by InterFAX to identify its users.

First, you will need to set this requirement in your user account. After logging in to your account, go to My Settings > Outgoing Options > Allowed Emails > Authentication. Check the Authenticate sender by password check box.

Now, each time you send an email, add your password somewhere in the message body in the following format: !#password. For example, !#123452.

This entry will be automatically stripped from the outgoing fax. Should the password be missing or incorrect – the fax will not be sent.

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Getting status

This page explains how to view the status of faxes sent via our SMTP fax interface. The email interface does not directly enable viewing the status of your outgoing fax queue. However, a variety of methods exists to enable confirmation of faxing activity.

Web-based account management

Your SMTP faxing activity, whether initiated from a programmatic email interface, from the Interfax Web Service, or any other way, will always be visible by logging into your account.

After logging in, go to Outbound Faxes to view all of your outbound faxes.

Confirmation email

You may elect to receive a confirmation email to report the completion of outgoing faxes. You may indicate which events will trigger such notification: On Success Only, On Failure Only, Always, or Never.

Configuration of this setting is performed through your account. After logging in, go to the Notifications tab in Outbound settings and choose an option for Delivery Status via Email.

The format of the confirmation email can be one of several options. See Fax feedback formats for more information.

Note: If you send SMTP faxes to several destinations at once, by entering more than one address into the “To:” field, you will not receive confirmations for every single recipient. Instead, you will receive a single email, detailing the outcome of transmission to all destinations. The email will be sent upon completion of all transmissions.

InterFAX web service

The InterFAX Web Service may be used to programatically retrieve information about outgoing faxes. See Outbound fax web service for more information.

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Usage examples

This section provides usage examples for developers wishing to use our fax SMTP interface to send faxes automatically.

The email message may be generated from any environment that can send a standard SMTP email. The following examples show syntax and required fields for the most popular SMTP fax scenarios.

Email body only

Below is a code sample showing how to send a fax using the SMTP interface, inserting the content of the fax message into the SMTP body.

From: sender@sendaddress.com
To: +1(212)555-9999@fax.tc
Subject: Here's a test fax 

Message: Here comes a long message. If there is no file attachment, the message body is sent.

Attachment only

Below is a code sample showing how to send a fax using the SMTP interface, by adding the fax content as an attachment, and instructing the system to ignore the email body.

From: sender@sendaddress.com
To: +1(212)555-9999@fax.tc
Subject: Here's a test fax 
Attachment: Quotation.doc

Message: This message will be ignored and only the attachment will be sent because there is no /b modifier at the end of the subject line.

Email body and attachment

Below is a code sample showing how to send a fax using the SMTP interface, by adding an attachment, and instructing the system to send both the SMTP body and the attachment in the fax message.

From: sender@sendaddress.com
To: +1(212)555-9999@fax.tc
Subject: Here's a test fax /b
Attachment: Quotation.doc

Message: In this case both this message body AND the attachment will be faxed because there is a /b modifier at the end of the subject line.

Deferred transmission

This is a code sample showing how to send an SMTP fax at a future time.

From: sender@sendaddress.com
To: +1(212)555-9999@fax.tc
Subject: Here's a test fax /d 2002-12-31 00:45

Message: In this case the message will be faxed at a later time. The /d modifier works with the following date format: yyyy-mm-dd hh:mm. If no date is entered, the current date is assumed.

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Destination number notation rules

See Fax number formats for more information.

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Error conditions

This page explains how to deal with errors received when sending faxes automatically using our fax SMTP gateway.

The InterFAX service is a hybrid mail/fax server and will issue error messages within the SMTP communication stream, where possible. This provides a standard error-notification mechanism which captures errors, such as unidentified senders or malformed destination addresses, which may be returned immediately to the sender encapsulated as an email error condition.

For a definition of error codes see Fax status codes.

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