How Does PostalMethods Work?

PostalMethods is a web-to-letter service which accepts messages submitted over the internet and sends them out as postal letters (snail mail).


Messages may be submitted via the following protocols.

SMTP Email

Emails can be sent to with one or more attachments (either pdf, doc, docx or html), of which the first page of the first document needs to be properly-formatted to align to a window envelope.
(See also How To Send A Letter By Email)

XML Web Service (SOAP)

The service can be accessed via SOAP at these service end points. A variety of sending, status retrieval, and control methods are available.


Most methods that are available via SOAP are also available via HTTP POST except for sending letters and postcards methods.

Addressing Types

PostalMethods differentiates between two types of message:

  1. Messages in which the destination address is present in the document ("address inside").
  2. Messages in which the destination address is not present in the document. Instead, the address is provided in the Web Service call that transports the document to PostalMethods ("address outside").

(See also "Address Inside" or "Address Outside"?")


Once a message is successfully received through one of the above-mentioned access methods, PostalMethods performs the following actions on the message:

  1. Authenticates, validates and logs the request
  2. Separates all attachments - e.g. MS Word, HTML, PDF documents (see Supported File Types) and converts them to a common format - a single, possibly multi-page, PDF document.
  3. If "address inside": extracts destination address from the document, verifies that it adheres to local standards using Address Verification & Correction, fixes it if needed and stamps it in the proper location, overwriting the existing address.
  4. If "address outside": collects destination address from the Web Service call, verifies that it adheres to local standards using Address Verification & Correction,
    fixes it if needed and stamps it in the proper location.

  5. Prints PDF, folds page(s), inserts into an envelope, closes, stamps (franks), and delivers letter to a postal distribution center.

(See also How PostalMethods Handles Postal Addresses)


PostalMethods methods enable several categories of functionality using Web Service request for sending letters and postcards; retrieving the status of sent mail items; retrieving the contents and metadata of a letter; cancelling mail (if possible); retrieving the rendered document; and more.

(Find the most accurate control options regarding the Postal Web Services)


Determining the status of a letter can be achieved by "pull" or by "push":

Feedback by "pull"

In "pull" feedback, the client system (your server) initiates a call to query the status of a letter. PostalMethods is contacted with one of the query methods and responds accordingly. The client system needs to poll PostalMethods until a final status is returned. This may require multiple attempts. The methods listed in the Retrieving the status of one or more letters section above are "pull" methods.

Feedback by "push"

In "push" feedback, the PostalMethods system initiates a call to the client system once the status of a letter changes. The developer can decide whether to receive feedback by HTTP POST, by SOAP callback, or by email confirmation. In each case, the developer can also indicate to which URL, endpoint, or email address, respectively, feedback should be sent. In "push" feedback, the PostalMethods system does not need to be polled repeatedly, and only one call is placed back to the client for each change of status.

(See also "Push" vs. "Pull" Feedback)

Setting Preferences & Defaults

PostalMethods includes a wide variety of settings that can be set through the online control panel. See the Setting System Preferences section for an overview of the important settings.