If either the Store in Mailbox or the Store in Mailbox and Folder option is selected, messages are stored in the account file. The account file format is the same as used with most Unix mail servers - a plain text file containing messages separated with an empty line followed by the From-line. The From-line starts with the letters From and a space, and it contains the message return path, the delivery timestamp, and the unique message identifier.
Sometimes a message cannot be stored immediately because the account file is locked by some other Server process (for example, the POP module may be serving a client that uses this account), or some other application. In this situation, the Local Delivery module leaves the message in the queue and then the module retries to deliver that message every 30 seconds.
Senders can request return-receipts by including the Return-Receipt-To: header fields into messages.When a message containing a Return-Receipt-To: header field is delivered to a local account, the Server generates a Return-Receipt message and sends it to the address specified in the Return-Receipt-To: header.
If a message does not have a properly composed RFC header part, the Server adds an RFC header to the message. This header contains the required header fields only.
If a submitted message does not have a Date: header field, the Server adds one using the date and time when the message was submitted to the server.
If a submitted message does not have a Message-Id: header field, and the message was received from a "trusted source" (from a TCP address in the Client Hosts List, via AppleTalk, etc.), the Server adds a Message-Id: header to the message.
A user or an application can create a text file containing a messages in the RFC822 format and then move it to the Submitted folder inside the SIMS Folder. As soon as the server finds a text file in that folder, it copies it into its queues for delivery.
Text files placed in the Submitted folder should have the STR resource with the ID=8192 containing the Return-Path for the message, and the STR# resource with ID=8192 containing E-mail addresses of the recipients.
If one of these resources is not found, the message RFC822 headers are examined. The Return-Path address is taken from the From: message header, and recipients E-mail addresses are taken from all To:, Cc:, and Bcc: headers. In this case, all Bcc: headers are removed from the message.
If the message is submitted successfully, the text file is deleted from Submitted folder. If there is a problem with message processing (no recipient is specified, etc.), the text file is moved to the Trash.
The Submitted folder can be substituted with an alias pointing on any folder on any disk.
Files with names that begin with "X." are deleted without processing.