Panix Help System: Mail forwarding restrictions

Restrictions on Mail Forwarding

Panix offers several different options for forwarding mail. Because indiscriminate forwarding implicates our servers in the spread of spam and virus/worm mail, we require spam blocking and virus protection whenever mail from Panix is forwarded to another site. (Virus checking can be implemented via webmail or via procmail.)

The following restrictions apply

Mail forwarding from your Panix account: If you set your Panix mailbox to forward mail to an account on another site, we require that you turn on at least the default set of spam blocks (currently the Zen blocklist), Panix's anti-virus filter, and SpamAssassin.
Using the vacation program or a custom auto-responder: If you use a vacation program, or have your own software that replies to incoming mail, you must turn on the default set of spam blocks, anti-virus filtering, and SpamAssassin. When a vacation program or auto-responder sends mail to a forged return address, it becomes unwanted mail at that site, and many sites consider such "backscatter" to be just as bad as spam.
Mail aliases that forward to your Panix mailbox: An alias address that delivers to a single Panix mailbox will use the spam-blocking settings of that mailbox. Note that the default is currently to enable the Zen blocklist. To turn that off, you must log into webmail and explicitly disable the setting. Please note that an alias that forwards off-site, or to multiple destinations, will receive Panix's default spam blocking settings.
Mail aliases that forward to other sites: All aliases that forward mail to off-site addresses or to multiple users will be configured to use the Zen blocklist. Panix may also add additional spam blocking at our discretion to protect our network if these blocks are not sufficient.

Why we do this:: Supposing the address yourname@yourdomain (hosted at Panix) forwards to you@someplace_else. Any spam that comes to yourname@yourdomain will be forwarded to the server that handles the mail for someplace_else-- and it will come from Panix's servers. That means that any complaints about that spam will reflect on Panix's servers, even though it didn't originate here and passed through our server only because of the alias.; This can cause our servers to be blocklisted. When that happens, it interferes with the delivery of other customers' mail to correspondents at other domains.