You can apply either of the below patches and test. I had a different version of clamassassin and patch 1 worked for me. Idea is to fix/remove the multiline header which clamassassin is trying to add when it gets an error code other than 0 or 1. The source below is the debian package source and not what finally gets deployed on the system.
****** Patch 1 ****** --- clamassassin.in 2007-03-05 09:49:48.000000000 +0530 +++ clamassassin_fixed1.in 2023-12-11 01:16:47.649663604 +0530 @@ -147,9 +147,9 @@ MINOR=`${SIGTOOL} --stdout -i ${SIGLOC}/daily.cvd \ | ${SED} -e "/^Version: /!d" -e "s/.* //"` SIGVERS="${MAJOR}.${MINOR}" - VERSION="@PACKAGE_STRING@ with ${CLAMVERS} signatures ${SIGVERS}" + VERSION=`echo @PACKAGE_STRING@ with ${CLAMVERS} signatures ${SIGVERS}` else - VERSION="@PACKAGE_STRING@ with ${CLAMVERS}" + VERSION=`echo @PACKAGE_STRING@ with ${CLAMVERS}` fi # Have ClamAV check the message and save the simple results in the log ****** Patch 2 ****** --- clamassassin.in 2007-03-05 09:49:48.000000000 +0530 +++ clamassassin_fixed2.in 2023-12-11 01:17:40.621836298 +0530 @@ -187,8 +187,7 @@ else # If the result was not 0 or 1 then some sort of error occured ${FORMAIL} -f -I "X-Virus-Status: Failed" -I \ - "X-Virus-Report: ${CLAMSCAN} error ${RESULT}" \ - -I "X-Virus-Checker-Version: ${VERSION}" < ${MSGTMP} + "X-Virus-Report: ${CLAMSCAN} error ${RESULT}" < ${MSGTMP} bailiferr $? fi fi Regards, Shubhra Prakash Nandi Founder and CEO, ISUB SOFTWARES (OPC) PRIVATE LIMITED Phone: +91-9871482815