Russell from Port25 posted a comment on my earlier post about changes at Comcast.
Our (Port25) understanding is that Comcast is rate limiting such that they’re only accepting 6 recipients per second per sending IP.
This matches what I’ve been hearing from other bits of the industry over the last few days. I am recommending clients close the connection between each set of 6 email addresses.
I’ve been hearing rumors that some *.rr.com domains have been bouncing all mail sent to them. Those domains belong to customers that were moved to Comcast as part of the RoadRunner / Comcast / Adelphia purchase and customer swap. As a courtesy, RoadRunner forwarded mail to comcast for those former RoadRunner customers, but have ceased to do so.
Mail to any address in the following *.rr.com domains will no longer be delivered.
jam.rr.com
midsouth.rr.com
mn.rr.com
se.rr.com
sport.rr.com
swfla.rr.com
ucwphilly.rr.com
houston.rr.com
These addresses should be removed from your lists. These users now have Comcast addresses. You cannot just substitute the Comcast domain for the RoadRunner domain as users were required to choose new localparts. That means bobjones@houston.rr.com may not be, and probably is not, bobjones@comcast.
Last week I requested details about Yahoo rejections for IPs pointing to the PBL when the IP was not on the PBL. A blog reader did provide me with extremely useful logs documenting the problem. Thank you!
Based on my examination of the logs, this appears to be a problem only on some of the Yahoo! MXs. In fact, in the logs I was sent, the email was rejected from 2 machines and then eventually accepted by a third.
I have forwarded those logs onto Yahoo who are looking into the issue. I have also talked with one of the Spamhaus volunteers and Spamhaus is aware of the issue as well.
The right people are looking at the issue and Spamhaus and Yahoo are both working on fixing this.
Thanks for the reports and for the logs.
Yahoo has updated and modified their postmaster pages. They have also put a lot of work into clarifying their response codes. The changes should help senders identify and troubleshoot problems without relying on individual help from Yahoo.
There is one major change that deserves its own discussion. Yahoo is now using the SBL, XBL and PBL to block connections from listed IP addresses. These are public blocklists run by Spamhaus. Each of them targets a different type of spam source.
The SBL is the blocklist that addresses fixed spam sources. To get listed on the SBL, a sender is sending email to people who have never requested it. Typically, this involves email sent to an address that has not opted in to the email. These addresses, known as spamtraps, are used as sentinel addresses. Any mail sent to them is, by definition, not opt-in. These addresses are never signed up to any email address lists by the person who owns the email address. Spamtraps can get onto a mailing list in a number of different ways, but none of them involve the owner of the address giving the sender permission to email them.
Additionally, the SBL will list spam gangs and spam supporters. Spam supporters include networks that provide services to spammers and do not take prompt action to remove the spammers from their services.
The XBL is a list of IP addresses which appear to be infected with trojans or spamware or can be used by hackers to send spam (open proxies or open relays). This list includes both the CBL and the NJABL open proxy list. The CBL list machines which appear to be infected with spamware or trojans. The CBL works passively, looking only at those machines which actively make connections to CBL detectors. NJABL lists machines that are open proxies and open relays.
The Policy Block List (PBL) is Spamhaus’ newest list. Spamhaus describes this list as