[exim] Don't add received header for scanned mails

Hello,

I'm passing mails to spamassassin via a transport like:

spamcheck:
     no_verify
     driver         = accept
     condition      = ${if and {{!eq {$received_protocol}{spam-scanned}}{eq{$domain}{localhost}}}}
     headers_remove = X-Spam-Flag:X-Spam-Report:X-Spam-Status:X-Spam-Level:X-Spam-Checker-Version
     transport      = spam_check

spam_check:
     driver            = pipe
     command           = /usr/sbin/exim -oMr spam-scanned -bS
     use_bsmtp
     transport_filter  = /usr/bin/spamc -u $local_part@$domain
     home_directory    = /tmp
     current_directory = /tmp

I'm wondering if it's possible to NOT add new received header and a new
envelope-to header? I've concerns that this might affect relearning mails
if this headers are added or modified.

Best regards,
Matthias