Be careful of ISP SPAM filtering.
This is what happened to me...
I was using 56K dial-up through AT&T which used Prodigy as the e-mail pass-through. It has SPAM filtering which seemed to work so-so; however, some still got through. But basically my normal mail always got through (along with a little SPAM).
Then about 4 or 5 months ago I switched to SBC DSL which uses Yahoo e-mail filtering. All the SPAM stopped; I thought GREAT, at last.
Then little by little I began to notice that I was not getting certain e-mails anymore that I used to get. It was not too noticeable at first & I was still gaining experience with DSL. Over time I realized that many messages were not getting through.
I told SBC that I had no use for all the Yahoo stuff & all I wanted was a fast connection & to use my own browser (Opera) & e-mail program (Outlook) so I never looked at any of the Yahoo programs. I figured that if they wanted to give it to me for free so what, I simply would ignore it & continue using my own browser & e-mail programs.
That worked just fine until I began to realize that I was not getting some of my usual e-mails.
I called SBC DSL tech support & they suggested that I look at the Yahoo e-mail which I had never used before. Well... to make a long story short, that is where the SPAM filter is & it had over 90 messages for the last couple of weeks that never got through the SPAM filter including many, many Interact Forum notices to responses for my Forum questions. Some of Interact was getting through, but about half was not. The Yahoo SPAM filter would automatically delete any trapped message after 30 days so I have no idea how many messages I actually lost maybe 400 - 500 or so.
It turns out that unlike the AT&T Prodigy SPAM filter that has hard limits, the SBC DSL Yahoo SPAM filter has to be trained as to what kind of mail to stop & what is ok to pass. It works like this; it will stop a lot of mail at first. You go to your Yahoo Mail site from time to time & move those items that you do want to read to the Yahoo Inbox where they will be available to your normal e-mail program (in my case Outlook). This act of moving trapped mail to the inbox tells Yahoo SPAM filter that it is ok to pass this type e-mail in the future. In other words it is being trained.
I now am now getting all of my Interact notices along with all the other messages that I was not previously receiving.
Sooo... the bottom line about ISP provide SPAM filtering is to... CHECK IT, CHECK IT, and CHECK IT again on a regular basis until you are satisfied that the messages you really want are in fact getting through.
I know, this is double work checking both your regular e-mail & your ISP provided e-mail but in many cases that is a fact of life with the SPAM blight that is upon us today.