Sendmail/Blacklists rejecting authenticated users

Quick question regarding dnsbl's... The other day I was in the Pittsburgh airport trying to send an email using their free wifi. Unsurprisingly this network's ip range is listed on a few of the blacklists. This resulted in my mail server rejecting my connection when I tried to send some emails. Does anyone know how I can configure sendmail/procmail to not check the IP addresses against the dnsbls for authenticated users? I have already done a fair amount of googling but haven't come up with anything workable, nor can I think of a good way to test (since I don't have access to a blacklisted network). 

Thanks,
Mike