[Exim] Help with correct syntax in system_filter.exim

Hi

I am trying to customise the fail message for the system_filter.exim to
include a link such as
<a href="mailto:email@somewhere.com">Click to send email</a>
What would be the correct syntax, I get confused with all the \ and /
slashes!!

Any help would be appreciated.

Regards

Anthony

Anthony Warren
Medway Council
Tel:             01634 332375
Fax:             01634 332881
Mobile:            07968 312173
Email:             anthony.warren@???
Urgent Email (SMS):    anthony.warren@???