VERP header regex

[Opesh Alkara]

Can any one suggest me the REGEX that will work for all the VERP
headers....the VERP header format is something like this:

Example:

verp-prefix-username=userdomain.com at mailinglistserver.com

OR

listname-user=domain at your.domain

 If the return path is something at yahoo.com <http://yahoo.com> and the
recipient email is mynameisxyz at gmail.com, the verp address should be

 something-mynameisxyz=gmail.com at yahoo.com

The REGEX should be able to parse any VERP header....
 Thanks much...

--
Regards
Opesh Alkara