This ebuild contains this note: if [[ -n "${QMAIL_PATCH_DIR}" ]]; then eerror eerror "The QMAIL_PATCH_DIR variable for custom patches" eerror "has been removed from ${PN}. If you need custom patches" eerror "you should create a copy of this ebuild in an overlay." eerror die "QMAIL_PATCH_DIR is not supported anymore" fi but it doesn't clear are any user patches prohibited, or custom solution with QMAIL_PATCH_DIR is not supported while standard epatch_user is allowed.
Created attachment 499162 [details, diff] move to EAPI 6
netqmail-1.06-r6 ebuild has that included.