You may be getting blocked because your server is accepting e-mail with bad addresses and then generating NDRs rather than checking for valid e-mail addresses during the connection. We would wind up on SpamCop's lists when we still ran Exchange 5.5 because of these.
Both Postini and MessageLabs have an option to do non-account blocking based on the users populated in their lists. However, Exchange does have this facility as well and I recommend enabling it. There is a risk of spammers being able to find valid e-mail addresses, but you're going to have this issue no matter what if you use this type of service (though Postini will see this as a directory harvest attack). Also, it helps decrease your traffic as you are not accepting unnecessary e-mail and you do not generate unnecessary NDRs as the sending side will generate them when the Exchange server rejects the recipient. -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Evan Mann Sent: Tuesday, April 08, 2008 12:31 PM To: Exchange Discussions Subject: RE: Postini/MessageLabs/etc. Got listed with spamhaus CBL twice, and it's been picked up by barracudacentral.com now because of it and been rated poor, so anyome using a Barracuda is blocking the domain. Anyone using the spamhaus CBL is blocking the domain. I've ran the CBL test and the mail server is advertising an appropriate FQDN response, but that's not the only reason you end up on CBL. I know there is no open relay, all passwords on all accounts have been changed twice to hard password. All outbound port 25 is blocked except for the mail server. Mail server runs Trend SMB, plus I've done online housecall scan, so I'm a little confused as well. I'd love to get it fixed, but time is a concern. There is a TON of inbound spam, and GFI MaiLEssential's doens't catch enough (combined with Outlook Junk filter it's pretty good though). So, I have a good reason to go to a hosted service as well. I know Postini offers outbound as well, but I haven't spoken with someone to see what extra benefits it adds for 2.5x the cost. If I can send inbound and outbound e-mail through a hosted solution that will almost guarantee me that mail from the domain won't get blocked agian, then it's the route I'm going to go. Imanage this particular network as a side gig and rarely have time to put in to troubleshoot these types of problems. For 10 users, it's $30-150/mo for hosted transport, and I've already told them they may need to incur that cost, and they seemed fine with it. -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Christopher Harris Sent: Tuesday, April 08, 2008 1:21 PM To: Exchange Discussions Subject: RE: Postini/MessageLabs/etc. Hi Evan, If your client's IP is getting blacklisted, then it's unlikely that the issue is spoofed spam. I haven't found anyone yet who can spoof an SMTP neighbor's IP address. If the IP's getting blacklisted usually it means that the IP is open for relay or that the client is a spammer or sending email for spammers. Which blacklist was the client on? One of the public ones such as spamhaus or an ISP blacklist? What responses did their server receive from the recipients MTA? What's the IP of their server? A hosted spam solution may be right for the client, and with only 10 mailboxes it's not going to cost them much, but such services are primarily intended to block inbound spam/viruses and prevent viruses from being sent inadvertently. Sounds like an interesting issue. Give us some details and I'll see if I can help you out. -Chris -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Evan Mann Sent: Tuesday, April 08, 2008 11:57 AM To: Exchange Discussions Subject: Postini/MessageLabs/etc. Looking for some input on services such as Postini, MessageLabs, and others. I have a small business that is having some issues getting DNS blacklsited. The first time it was virus related, but that was solved, now it's due to spoofed spam. Looking for a service that will smarthost oundbound mail and hopefully eliminate the problems that the business is having now with their actual Ip that Exchange is hosted on being blacklisted. Also want the benefits of spam/av protection for inbound. There's about 10 mailboxes that need to be protected. _________________________________________________________________ List posting FAQ: http://www.swinc.com/resource/exch_faq.htm Web Interface: http://intm-dl.sparklist.com/read/?forum=exchange To subscribe: http://e-newsletters.internet.com/discussionlists.html/ To unsubscribe send a blank email to [EMAIL PROTECTED] t.com Exchange List admin: [EMAIL PROTECTED] To unsubscribe via postal mail, please contact us at: Jupitermedia Corp. 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