by chow » 8:46pm, Thu 01 Feb, 2007
Yes, most mail server spam filters generally filter messages based on IP addresses. Yes, header info is a common give away of Spam, however many software spam filters (ie client end) filter by looking for similar text patterns, hence, spammers send advertising spliced among random text from books etc. The spam filter looks to see if any more that a certain percentage of the message text (plain or html) matches that of any messages that have already been tagged as spam. Therefore, if your user has received a message from someone else using phplist which they have previously tagged as spam, it could quite well tag your message as spam, particularly if you are sending short messages, in which case, the phplist logo will make up a larger percentage of your message. And once again, you pay for someone else's abuse of the system!
My advice: credit where credit is due; don't comment out the phplist logo, simply exchange it for some other unique code - that way you can also customise it to suit your mail template so it is not obtrusive.