ISP's have blocks of IP addresses that are reserved for Dynamic IP's. Get an IP and a subnet mask and it's not too hard to figure out the block of addresses.
I don't know the exact specifics of how AOL for instance is doing this, but it is usually fairly easy to block or reject mail coming from specific IP's, or in their case, they have the ability to reject an entire netblock. The method of inspecting it is the same as spam filters. They check the headers of the e-mail before allowing it to pass. Or they check the subject line, etc. It all works the same way. Ben Winzenz Network Engineer Gardner & White (317) 581-1580 ext 418 -----Original Message----- From: Jim Helfer [mailto:[EMAIL PROTECTED] Posted At: Thursday, July 31, 2003 9:37 AM Posted To: Exchange (Swynk) Conversation: Anyone else having trouble with AOLs new SPAM rules? Subject: RE: Anyone else having trouble with AOLs new SPAM rules? This is going over my head, I'm afraid. How can the accepting host know that the sending server has a dynamic IP address? Surely it's not changing in the middle of a mail send? Is the recipient doing a reverse DNS lookup or something? Trying to learn something in Pittsburgh Jim Helfer Greg Sachs wrote: > I've had problems from a dynamic dns site on a cable modem sending to > aol for a long time. ISP's smtp server is the only way to go - > smarthost is one way, you can also set up an smtp connector to send > mail to specific domains to your isp's smtp server such as aol.com. > Your choice if you trust your isp's mail server more, or your ability > to keep the list on your connector current for domains that won't > except your outgoing email directly > > -----Original Message----- > From: Dickenson, Steven [mailto:[EMAIL PROTECTED] > Sent: Thursday, July 31, 2003 9:12 AM > To: Exchange Discussions > Subject: RE: Anyone else having trouble with AOLs new SPAM rules? > > > Use your ISP's SMTP server as a smarthost for all outgoing mail. > > Steven > --- > Steven Dickenson <[EMAIL PROTECTED]> Network Administrator The > Key School, Annapolis Maryland > > -----Original Message----- > From: Bubba G [mailto:[EMAIL PROTECTED] > Sent: Thursday, July 31, 2003 9:12 AM > To: Exchange Discussions > Subject: Anyone else having trouble with AOLs new SPAM rules? > > > I have architected for Fortune 10s... but this time I have a small > server on a home network. I use DynDNS.ORG to update the A and MX > records. AOL has just instituted a new policy rejecting any email > server coming from a dynamic IP address. I have emailed them asking > about this but I know they will respond with something like "We are > attempting to reduce SPAM"... even though I reject SPAM on my server's > SMTP connector based on IP because SPAMmers typically use the same > ISPs and static IP addresses... and there are only a handful of ISPs > that allow spammers knowingly. > > Anyone else had problems with this lately... or more importantly found > a way around it (other than getting/paying for a static IP address)? > > > _________________________________________________________________ > List posting FAQ: http://www.swinc.com/resource/exch_faq.htm > Web Interface: > http://intm-dl.sparklist.com/cgi-bin/lyris.pl?enter=exchange&text_mode > =& > lang > =english > To unsubscribe: mailto:[EMAIL PROTECTED] > Exchange List admin: [EMAIL PROTECTED] > > _________________________________________________________________ > List posting FAQ: http://www.swinc.com/resource/exch_faq.htm > Web Interface: > http://intm-dl.sparklist.com/cgi-bin/lyris.pl?enter=exchange&text_mode > =& > lang=english > To unsubscribe: mailto:[EMAIL PROTECTED] > Exchange List admin: [EMAIL PROTECTED] > > _________________________________________________________________ > List posting FAQ: http://www.swinc.com/resource/exch_faq.htm > Web Interface: > http://intm-dl.sparklist.com/cgi-bin/lyris.pl?enter=exchange&text_mode=&; lang =english > To unsubscribe: mailto:[EMAIL PROTECTED] Exchange > List admin: [EMAIL PROTECTED] _________________________________________________________________ List posting FAQ: http://www.swinc.com/resource/exch_faq.htm Web Interface: http://intm-dl.sparklist.com/cgi-bin/lyris.pl?enter=exchange&text_mode=&; lang=english To unsubscribe: mailto:[EMAIL PROTECTED] Exchange List admin: [EMAIL PROTECTED] _________________________________________________________________ List posting FAQ: http://www.swinc.com/resource/exch_faq.htm Web Interface: http://intm-dl.sparklist.com/cgi-bin/lyris.pl?enter=exchange&text_mode=&lang=english To unsubscribe: mailto:[EMAIL PROTECTED] Exchange List admin: [EMAIL PROTECTED]
