We are running an email server (RH9) using sendmail. After Comcast upgraded / migrated a year or so ago, we started having problems connecting with their email server. As we aren't a Comcast customer, they're not much help and claim they haven't changed anything, yet they admit they just migrated / upgraded all their email servers. If we send email to a comcast email address, we just get a "connection timed out" error. We seem to function with everyone else. Any ideas?
Please check if you have proper SPF and reverse records for your domains. Also make sure you're not blacklisted: http://mxtoolbox.com/blacklists.aspx
