Status update:
Less is apparently more. Removing the condition lines here and there,
such as:
condition = ${lookup mysql{SELECT email_username FROM league WHERE
email_username='$local_part_data' AND domain='scasl.ca'}{$value}fail}
allowed email from external senders to go through. Dovecot took care
of the rest.
The vmail aliases function works with ${quote_mysql:$local_part} but not
with $local_part_data. Go figure.
Thank you for the suggestions; they all helped.
Cam
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