Microsoft Entourage has no setting to attach your vCard to outgoing messages. You can drag your me contact from the Address Book to the message every time, but that soon becomes tedious. Instead, you can run the following script, which also uses AppleScript's read/write commands and some Finder scripting to update your vCard, and then attach it. If want to send your vCard with every message, set the script to run from a repeating schedule every one minute.

tell application "Microsoft Entourage"
	set MUDpath to (path to MUD) as Unicode text
	set meContact to me contact
	set vcInfo to vcard data of meContact
	set myname to name of meContact
end tell

set pathName to (MUDpath & myname & ".vcf") as Unicode text
 
try
	set f to open for access file pathName with write permission
	--will create a new one or update every time
	set eof f to 0
	write vcInfo to f
	close access f

	tell application "Finder"
		set creator type of file pathName to "OPIM"
		set file type of file pathName to "vCrd"
	end tell
     
	set theVcard to alias pathName
     
on error errMsg number errNum
	try
		close access f
	end try
	beep 2
	return
end try
 
tell application "Microsoft Entourage"
	try
		if class of window 1 ≠ draft window then error number -128
	on error
		return
	end try
	set newMsg to window 1
 
	set theAttachments to every attachment of newMsg
	repeat with theAttachment in theAttachments
		-- only one, don't multiply vCards
		if name of theAttachment = (myname & ".vcf") then return
	end repeat
     
	make new attachment at newMsg with properties {file:theVcard}

end tell

The first part of the script gets the path to MUD, the path to the Microsoft User Data folder, where you are going to store your vCard. Although you don't realize it when you make vCards in the UI, Entourage must have it as a file on your hard disk to be able to make an attachment to a message. You could make it in the Entourage Temp subfolder there, where Entourage makes vCards that are dragged to a message, but instead, using this script, you can make it right in the MUD folder to have it easily available in the UI, too.

Entourage requires (and won't let you delete) a me contact, so the line that gets it will never error. There is a property of contact called vcard data, which contains all the data in text form, that makes up a vCard. You also need the name of your me contact to become the name of the vCard.

The next section of the script, after the first Entourage block, creates the vCard file. First you compose the full path of the file that you are creating: the path to MUD, plus your name, plus the .vcf extension.

The next group of commands comes from the Standard Additions whose dictionary you can find in Macintosh Script Editor. Find the File Read/Write Suite.

To write to a file, you need to open for access file [pathname] with write permission. That creates a new file if it doesn't exist yet, or accesses it if it does. The command set eof f to 0 erases it (you are about to update the vCard, which might have out-of-date information from the last time). You then write the vcard data to the file and close it. Always put a write command inside a try/error block, and try to close access the file if there's any sort of error. It is not recommended that you leave a file with open access.

On most Macintosh computers, the Address Book that comes with the operating system is the default "owner" of .vcf (vCard) files. So the file would appear with the Address Book program's vCard icon. You must tell the Finder to set the file's creator type to OPIM — the Entourage 4-character signature (creator type). Also tell the Finder to set its file type to vCrd to get the correct Entourage icon, which is vCard, not database, message folder, or anything else.

Back in Entourage, check that the front window is a draft window and check for existing attachments. If the script is running from a schedule every one minute, you don't want it multiplying the vCard by adding a new copy every minute. So if you find that there already is an attachment with your name and .vcf, you quit the script (return) without doing anything. Otherwise, proceed to make a new attachment at the draft window using the alias object as the file property for the attachment. Whenever you send off the message, it will take your vCard with it.

Using a reverse process, you could make new contacts in your Entourage Address Book by running a script (possibly from a mail rule filtered on messages with attachments whose names contain .vcf) to save .vcf file attachments to your hard disk. For example, you could save them in a subfolder for vCards in the MUD folder, or somewhere temporary, and then delete the files at the end of the script. Then use the read command to read as Unicode text the file into an r variable and then, in Entourage, make new contact with properties {vcard data:r}.

However, this script could backfire if the vCard was sent using the Mail and Address Book applications that come with the operating system, or some other applications that make vCards differently. Entourage uses Unicode text, which is why writing the vcard data worked well and why you need to read it back as Unicode text. However, other applications on the Macintosh write vCards as plain text (string).

In addition, the Address Book that comes with the operating system now follows a different protocol, so it cannot be adjusted for Entourage. If you read one of those vCards as Unicode text, the resulting Entourage contact appears to be completely blank.

The following option should work, given that Entourage is the only application with Unicode vCards. A short test that checks for the presence of a byte-order mark (BOM) of hex-characters FEFF — ASCII characters 254 and 255 — as the first two characters of the text should suffice. If the text begins with the BOM, it's Unicode UTF-16 as made by Entourage vCards; if not, it's a plain text vCard that is not compatible with Entourage.

set r to read theVcard -- an .vcf alias (file) on your computer 
if (ASCII number (character 1 of r2)) = 254 and ¬     
	(ASCII number (character 2 of r2)) = 255 then -- checks for Unicode
	set r to read theVcard as Unicode text -- gets the data correctly
	tell application "Microsoft Entourage"
		make new contact at address book 1 with properties {vcard data:r1}
	end tell
else
	beep
	display dialog "This vCard is not from Entourage and cannot be " & ¬
		"imported as a contact. Sorry." buttons {"OK"} default button 1 ¬
		with icon 0
end if