Why does Sympatico block all SMTP servers except its own?
Sympatico blocks all traffic (incoming and outgoing) through port 25, except for it’s own SMTP servers. The main reason that Sympatico does this is to avoid being being blacklisted for spam (junk e-mail). Here’s why: A common feature of SMTP servers is open-relaying. Open-relaying allows anybody on the internet to relay an email message through an SMTP server. The disadvantage of open-relaying is that it makes all messages appear to originate from the relaying server. For this reason, open-relaying is usually disabled because a spammer could use an SMTP server with an open-relay to send spam, and it would appear that the owner of the SMTP server is sending the spam instead of the spammer. This makes it very difficult to trace the origin of the spam and stop it. If a Sympatico customer were to operate their own SMTP server, it is possible that it may be configured improperly with open-relaying enabled, and have spam relayed through it. In this situation, it appears that a Sympatico cust
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