[Exim] Auth server_condition problem

Hi

I have problem how check password via. pwcheck and mysql in one(?) condition.
I want make something like this:

first password check by pwcheck
${if pwcheck{$1:$2}{1}{0}}
and if authentication is success then ok - send mail, but if user dont
exist or password is wrong, check password from mysql db.
${if eq{${md5:$2}}{${lookup mysql{SELECT password FROM \
vmail WHERE username='${local_part:$1}'}{$value}}}{1}{0}}

Thanks

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Tomasz Krynicki