permit_mynetworks + check_recipient_access

I suspect this has been answered before as it must be a common config, but
I can not find any info... sorry if its an FAQ

I want postfix to act as an outgoing SMTP for my local hosts (mynetworks)
and also relay for some domains (relay_domains) for everyone.

So I tried:

smtpd_recipient_restrictions =
permit_mynetworks,
check_recipient_access hash:recipient_access

But this does not check validity of recipients when mail is coming from
localhosts.

If you reverse them:

smtpd_recipient_restrictions =
check_recipient_access hash:recipient_access,
permit_mynetworks

But this will prevent local hosts from sending to domains other than my
relay domains (eg, local hosts sending to foobar.com.)


Note: My hash:recipient_access list has all _valid_ accounts for my
relay_domains.

How are people doing this kind of thing?

--
Adam