Email Reference


Postal letters can be sent through PostalMethods by simply sending an email message with an attachment. The attachment needs to be of a supported file type, and its first page must include the recipient address block in the proper location.
See our Send A Letter From Any Email Program guide for step-by-step instructions.

Access by SMTP (Email)

Submit messages by email to

Email Message

Add documents, containing the content of the postal letter, as attachments. Any content appearing in the email body is ignored.

"From:" Address

The originator of the email message must be an Allowed Email Sender (see Setting System Preferences -> Allowed Email Senders). Messages from unauthorized senders are rejected by the email server upon arrival, with an error message of 550 Unauthorized sender within the SMTP stream.

Subject Line Content

Any content in the subject line is displayed in the My Description field within the control panel's Activity table, and is for reference only. Note that subject line switches are stripped from this description.

Subject Line Switches

You may override default settings by adding "switches" to the subject line. Placing a switch anywhere in the subject line will cause PostalMethods to ignore the default setting in the control panel's "User Settings".

  Switch Description
Mode /Production or /Development Overrides the Work Mode setting



Content delivered by email is treated as having its "Address Inside". This limits the document containing the recipient address to specific file types defined (see the earlier link).

Single Or Multiple Document Attachments:
All attached documents are used to create a single letter. Attachments are handled in the order in which they were attached. The first page of the first document must contain the recipient's postal address in the correct location. You can use a pre-fab template as your document to get started quickly.

ZIP File Attachment:
To send multiple letters in a single email message, attach a single ZIP archive of multiple supported documents. The ZIP file is extracted and each document is treated as an individual letter. Unsupported documents within the ZIP are ignored. Do not use password protected ZIP files. Be aware that some email servers are limited by the size of the email attachment they can handle.


In various stages of handling a letter, PostalMethods will "push" feedback back to the sender.

When the feedback method is Email, feedback is returned to the Reply-To address, or if unavailable, to the From address of the email message which originated the letter. This behavior can be overridden by setting a "Default Feedback Email" in "User Settings" -> Feedback -> Email -> Advanced Settings -> Default Feedback Email.

When the requested feedback method is set to SOAP XML or HTTP POST, feedback is sent to a supplied URL.

Encrypt Email Messages

The security of messages sent through the PostalMethods system may be enhanced by encrypting your emails. Encrypting your messages secure the contents of your message while it is in transit from your computer to our servers.

Developers please note: When using the PostalMethods Web Service Postal API, you may use SSL to access our servers securely. Read more.


Securing messages sent to PostalMethods:

  1. Obtaining the PostalMethods public key signature: Contact us and request our certificate
  2. Install the PostalMethods certificate: You must install the certificate on the computer or server where your message will be encrypted
  3. Encrypting your messages: When sending your email messages, make sure your email client or application uses the PostalMethods certificate to encrypt messages