[exim] Check for a particular header in exim router

Hi,

Is it possible to compare for a particular strings in header:

Something like the one given below:

-----------------
mycustom_route:
    driver = dnslookup
    condition = "Check if the email header contains the string
"X-Mail-Forwarder"            --- Not sure how to achieve this
    ignore_target_hosts = +loopback : 64.94.110.0/24
    headers_add = "${perl{mailtrapheaders}}"
    transport = remote_smtp
-----------------

Please let me know if any queries.

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Regards,
Soumya