This article series contain two articles, in first article I provide Theoretical Basics information of pickup directory, how works and importance of pickup directory. In the second article I’ll describe how to configure pickup directory using Exchange management shell.
By default pickup directory exists in "\Transport Roles\Pickup" of installation directory on every Exchange 2007 computer that has installed Edge role or Hub role. If you formatted .eml file and placed in the pickup directory, pickup directory will submit to delivery. This method used by most Exchange Administrator for mail flow troubleshooting their emails by creating .eml files.
How Pickup Directory process messages
Correctly formatted messages that copied to pickup directory is processed for submission for delivery as fallowing order.
- Pickup Directory checked for new email messaged every 5 seconds and you can’t change that time interval.By default pickup directory processed 100 messages and messaged are cannot open left in the directory for next pool.
- Limits that are messages in pickup directory checked.By default maximum header size is 64K and maximum recipient limit is 100 recipients.
- eml file rename to .tmp file.if .tmp file already exists it is renamed as a <file name><Date time>.tmp.If the file renaming fail, pickup process proceed for next eml file with generated event log.
- After the .tmp file converted to the email message, a “Delete on Close” command is issued and tmp file still exists but can’t open file by anyone else.
- after submitted the message to delivery ,a “Close” command issued,.tmp file is deleted from pickup directory.If deletion is failed, event error generated in event log.If transport services restated all .emp files are renamed to .eml files and start repressing messages.That could lead to duplicate mail messages transmission.
Requirements for Message Files in the Pickup Directory
A message file that is copied to pickup directory must be meet following conditions.
- The message file must be a simple text file that contain with basic SMTP message format.
- A message file extension must be a .eml.
- At least one email address must be exists in from: or sender message header fields. If a single email address exists in the both from or sender filed,email address in the from: filed used as the originator of the message in the message envelop.
- Only one email address can ever exist in the send filed.The sender filed is not required if email address present in From: filed.
- Multiple e-mail addresses are allowed in the
From:field, but a single e-mail address must also exist in the
Senderfield. The address in the
Senderfield is then used as the originator of the message in the message envelope.
- At least one e-mail address must exist in the
- A blank line must exist between the message header and the message body.
Please see below example of text message that uses acceptable message formatting for the pickup directory.
Subject: Test message
This is test Message to check mail flow.
MIME contain messages are supported in pickup directory.Please see below example that is compatible with pickup directory
Subject: Message subject
Content-Type: text/html; charset="iso-8859-1"
<TR><TD>cell 1</TD><TD>cell 2</TD></TR>
<TR><TD>cell 3</TD><TD>cell 4</TD></TR>
In here I am given you basic Theoretical information of pickup directory. I’ll show how to configure pickup directory in next article called "Configuring and Managing pickup directory-Part 2 ".