[Exim] pcre for several recipients with same username

I am trying to figure out how I can block emails that have several
recipients with the same username. (Examples below after signature.)

This sometimes works for me:

if $header_cc matches
"${original_local_part}@.*,[\n]*.*${original_local_part}@.*,[\n]*.*${original_local_part}@.*"

But it doesn't seem to work for other tests I have tried.

I have also tried:

if $header_cc matches
"${original_local_part}@.*,[\n]*.*${original_local_part}@.*,[\n]*.*${original_local_part}@.*"
or $header_cc matches
"${local_part}@.*,[\n]*.*${local_part}@.*,[\n]*.*${local_part}@.*"

Any ideas on a PCRE or other methods for blocking spams that have numerous
recipients all with the same username?

Jeremy C. Reed

Some examples:

To: webmaster@???
Cc: webmaster@???, webmaster@???,
     webmaster@???, webmaster@???,
     webmaster@???, webmaster@???,

To: reed@???
Cc: reed@???, reed@???, reed@???, reed@???,
     reed@???, reed@???, reed@???,
     reed@???, reed@???, reed@???, reed@???,

To: jreed@???
Cc: jreed@???, jreed@???, jreed@???, jreed@???,
     jreed@???, jreed@???, jreed@???, jreed@???,
     jreed@???, jreed@???,