For anyone running a mail server that has to use shawmail.wp.shawcable.netas the smarthost, it has a limit of 1,000 messages/day before it cuts you off for 24 hours. I suspect it might be closer to 2,500 [0], but the CSR at Shaw told me 1,000. Normally you wouldn't run into this, but as it turns out all the email coming in to my server gets relayed to gmail, including the spam.
You can see if you're under the ban:
# telnet shawmail.wp.shawcable.net 25 Trying 64.59.128.135... Connected to shawmail.wp.shawcable.net (64.59.128.135). Escape character is '^]'. 4.5.9|Spam limit has been reached. Connection closed by foreign host.
Sean
0. I had 2,700 some messages in my queue yesterday when under the penalty and only ~100 this morning after it was lifted (and subsequently put back in place after flushing the ~2600 messages)