Spam filters: do they filter based on the sender's IP address?

[Superwormy]

OK, so say I send an email message, and it gets sent from my home computer, to my SMTP server, to another guy's SMTP server, to his home computer.

Now, assuming we place a spam filter on his home computer or his SMTP server... does that spam filter check my home IP address or just the IP address of my SMTP server? I.E.: If I send a email, is my email going to get considered spam because its coming from my no-name ISPs IP address block range?

 

[cubby1223]

If there is no reason for your ISP to be on a blacklist, it will not be. As long as the mail server is properly configured and no user has been pushing through a lot of spam through that mail server, it shouldn't be blacklisted by anyone.

 

[nweaver]

Originally posted by: cubby1223
If there is no reason for your ISP to be on a blacklist, it will not be. As long as the mail server is properly configured and no user has been pushing through a lot of spam through that mail server, it shouldn't be blacklisted by anyone.

incorrect....most modern filters blacklist ISP subscriber IP's (dynamic) because reverse lookup fails.

the answer: it depends on the filter. Some will filter on from/to addresses, some will filter on smtp blacklists, some can be configure to flag anything from a dynamic/ISP ip, etc

 

[corkyg]

Spam ID and filtering is a complex process. It can be by sender, by domain, by text content, and host of things that can add up and be scored.

The simplest almost impenetrable Spam wall is the use of a white list only. IOW, all email not from a designated sender is rejected. Most ISPs refuse to do that - it would cut into their own Spam clients business. It is an option in AOL - always has been. That is one of their few really strong points.

Some ISPs approach that by requiring an authetication from any sender not already on the white list. Earthlink has that option. A plus!

 

[cleverhandle]

I think you're asking something different than what the replies are answering...

Originally posted by: Superwormy
Does that spam filter check my home IP address or just the IP address of my SMTP server?

It will check the address of your SMTP server, not the client connecting to it. It's your server's job to make sure that it only relays for the appropriate IP, but the filter should only look at the server IP itself.

 

[corkyg]

Good point! It checks whatever you set as the criterion. If it is an IP adress, then so be it. Usually it is a name or a domain. Folks don't usually memorize or know their IP addersses.

Spam filters are like all computer programs - they do what they are told to do, no more - no less.