IIS SMTP Service Overview

When the SMTP service is installed, it creates a directory called MailRoot in your default wwwroot folder. MailRoot has a number of subdirectories that are used for the processing of SMTP Mail. The names and purposes of these subdirectories are as follows.

Mailroot\Pickup

The Pickup directory is used as the primary location for outgoing mail messages. Whenever a mail message is placed in this directory, the SMTP service will pick up the message and process it. This means that you can copy a text file into this directory and, if it is in the correct format, it will be sent as a mail message.

Mailroot\Queue

After a message has been retrieved from the Pickup directory, SMTP attempts to send it immediately. If the message cannot be sent immediately, it is placed in the Queue directory and the SMTP service attempts to resend the message at regular intervals. The number and frequency of retries can be configured on the Delivery tab of the property sheet for the SMTP site in the Microsoft Management Console.

The Queue directory also contains transcript files. These are text files and have either an LTR (local transcript) or RTR (remote transcript) extension and can be used to determine the reason for the non-delivery of a particular mail message.

Mailroot\BadMail

If a message cannot be delivered (and the maximum number of retries has been exceeded) and the message cannot be returned to the sender as undeliverable, it is placed in the BadMail directory. After installation, the location of the BadMail directory can be changed on the Messages tab of the property sheet for the SMTP site in the Microsoft Management Console.

Mailroot\Drop

This is the location for incoming messages for all of the local domains that make up a particular site. Note that there is only a single Drop directory for all users on all local domains. The SMTP service within IIS 4.0 has no concept of local mailboxes, and therefore delivery of incoming mail messages to individual mailboxes is not supported. However, inbound messages in the Drop directory can be read from an Active Server Page.

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