[exim] ACL - can it affect my outgoing mail?

I have worked on setting up an ACL and have asked about it here in the forum
before.
I finally got the ACL set up, using:

# Drop those not having an MX record for Recipient drop message = That is
not a valid email for this domain !domains = @mx_any/ignore=127.0.0.1

right after the ACL_RATELIMIT_BLOCK statement.

This bounces emails sent to the machine that don't have a corresponding MX
record matching thhe IP. Works great!
BUT, now when I try to send to an address from that account, I get this
error in SquirrelMail...

Message not sent. Server replied:

Requested action not taken: mailbox unavailable
550 That is not a valid email for this domain


Any ideas? It almost seems like it doesn't know drsceifers@??? isn't
on this machine...