nbCrockett, you are not totally correct.
Most plain text systems will recognize links in emails.
However, you cannot include the HTML <a href=""></a> tags in the plain text email.
If you want to use your code, just do:
"Your order ID is " & Request.Form("L1") & " ." & ( vbCrLf & vbCrLf ) & "Be sure to include your order ID when sending your logo. To see logo size requirements, go to http://www.yahoo.com
FYI - You have a couple of grammatical mistakes in your resultant code. I know that may sound mean or obtuse, but if you are going to send this out, you need to fix these so that your customers are not put off by incorrect grammar. Also remember that a lot of phishing and spamming sites use incorrect grammar/spelling to catch people offguard. You do not want to be added to blacklists because of this.
To include a mailto: link in your email, for HTML mail you have the correct code. For plain text mail, just use
To email us, use this link: mailto:firstname.lastname@example.org