[exim] How to set timeout for command invoked in acl_data

Hi!
In acl_check_data are lines:
warn
message = ${run{/usr/local/bin/dspam-wrapper.sh
${spool_directory}/scan/${message_id}/${message_id}.eml }{$value}{$value}}

For a mails containing huge number of words, dspam needs above one, two
minutes to check mail. It seems that exim has timeout for run expansion
equal to one minute. In logs i'm getting:
failed to expand ACL message "${run{/usr/local/bin/dspam-wrapper.sh
${spool_directory}/scan/${message_id}/${message_id}.eml
}{$value}{$value}}": command timed out

Setting local_scan_timeout=10m doesn't change behavior (and probably
this is right:) ).
Is possible to change timeout for expansion variable in acl ?

Regards,
Marcin

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xmpp (jabber): marcin [at] mejor.pl