Make sure you insert them as an Outlook Item.
Make sure your message format is RTF.

Signature
Russ Valentine
[MVP-Outlook]
>I have created several distribution lists in Outlook 2003. Up until a few
> weeks ago I was able to attach them to a new message and send to someone
[quoted text clipped - 9 lines]
> see that the message went out with the correct attachment format.
> The recipient is also using Outlook 2003.
I had been inserting the lists as Outlook items, but I tried the RTF (and
Plain Text) without success. They appear to insert just fine (as lists), but
when received, they should up as mail items.
> Make sure you insert them as an Outlook Item.
> Make sure your message format is RTF.
[quoted text clipped - 11 lines]
> > see that the message went out with the correct attachment format.
> > The recipient is also using Outlook 2003.
Russ Valentine [MVP-Outlook] - 08 Jun 2005 23:34 GMT
Cannot repro that behavior. Plain text will not work. Make sure your
recipient isn't set to receive plain text only.

Signature
Russ Valentine
[MVP-Outlook]
>I had been inserting the lists as Outlook items, but I tried the RTF (and
> Plain Text) without success. They appear to insert just fine (as lists),
[quoted text clipped - 20 lines]
>> > see that the message went out with the correct attachment format.
>> > The recipient is also using Outlook 2003.
lowen - 08 Jun 2005 23:57 GMT
Have confirmed by trying to send list to myself (still comes across as blank
mail message). I am not set to receive plain text only.
> Cannot repro that behavior. Plain text will not work. Make sure your
> recipient isn't set to receive plain text only.
[quoted text clipped - 22 lines]
> >> > see that the message went out with the correct attachment format.
> >> > The recipient is also using Outlook 2003.
Russ Valentine [MVP-Outlook] - 09 Jun 2005 00:36 GMT
The only other cause for this I've seen is with some mail servers that alter
the attachment. Do you have another account you can try?

Signature
Russ Valentine
[MVP-Outlook]
> Have confirmed by trying to send list to myself (still comes across as
> blank
[quoted text clipped - 31 lines]
>> >> > see that the message went out with the correct attachment format.
>> >> > The recipient is also using Outlook 2003.