You trying to automatically hyperlink to bugs in your bug/defects tracking application?
Easiest thing to do would be to modify the software sending the email to create the hyperlinks itself...
If you still want to do it manually, here's a quick guide I hacked together that seems to work (tested VERY lightly, but it does nominally do what it's designed to do).
Step 1: Enable the Developer tab in the Ribbon
Click Customize Ribbon, then click the Developer checkbox:
Step 2: Go to VBA and put in the code
Click Visual Basic:
Double click on the ThisOutlookSession module and paste in the code as follows:
And now, the code:
Sub InsertHyperLink(MyMail As MailItem)
Dim body As String, re As Object, match As Variant
body = MyMail.body
Set re = CreateObject("vbscript.regexp")
re.Pattern = "#[0-9][0-9][0-9][0-9][0-9][0-9]"
For Each match In re.Execute(body)
body = Replace(body, match.Value, "http://example.com/bug.html?id=" & Right(match.Value, 6), 1, -1, vbTextCompare)
MyMail.body = body
Click the Save icon or press
Step 3: Create a Custom Rule executing a Script.
Go to Manage Rules & Alerts:
Click New Rule...:
Click "Apply rule on messages I receive", then click Next:
If you want to only run the rule on certain messages, you can select from any of the conditions here. Don't worry about filtering on messages containing "#123456" in the body; we do that in the code. So just filter on, for example, "From:" or the Subject, if you want. This is optional.
Choose "Run a script". Click on the text that says "a script" in blue underline in the bottom box.
Pick the script we just created, whose name will probably be cut off due to the small dialog, but that's OK.
At this point, you can just click "Next" and "Finish" at the bottom repeatedly until the dialogs go away; you should be done.
Now try and compose an email to yourself (or receive an email from the sender or subject line you're expecting, if you specified a custom condition) and insert a number like:
into the body, and send it.
When you get the mail message, it should have it as a URL to
http://example.com/bug.html?id=123456 (where "123456" is replaced with the 6 numbers you chose).
You can customize the script code to point to a different URL by modifying the URL string within the code. You can also do more exotic things with it to either keep or remove the number, or various other things.
This answer took my entire lunch hour, so if you think it was worthwhile, please remember to vote up... Let me know in the comments if you have any difficulties or questions.
Very Helpful StackOverflow question, which at least gave me a feasibility approach for implementing this: Append Subject Header in Outlook (VBA)