There has been a lot of recent discussion and questions about reputation, content and delivery. I started to answer some of them, and then realized there weren’t any basic reference documents I could refer to when explaining the interaction. So I decided to write some. This first post is about IP address reputation with some background on why IPs are so important and why ISPs focus so...
We’ve just about run out of the Internet equivalent of a natural resource – IP addresses. ICANN allocated the last couple of blocks of general usage IPv4 addresses to APNIC earlier today. There are just five usable blocks of addresses left, and they’re reserved by IANA policy for the final phase of IPv4 exhaustion, one for each RIR. Like any other resource that’s been...
The last of seven in our occasional series on why ESPs need, or don’t need, lots of IP addresses to send mail properly. I need multiple IP addresses in different locations so as to provide redundancy against blacklisting of my ISP Why this is right If you think that your email is likely to be blocked due to the reputation of your ISP then having a backup ISP makes some operational sense. Why this...
Number six of seven in our occasional series on why ESPs need, or don’t need, lots of IP addresses to send mail properly. I need multiple IP addresses in different locations to provide redundancy against network outages Why this is right If all your traffic goes out via a single ISP and your connection to that ISP is eaten by a backhoe you’re not going to be sending any email until...
Number five of seven in our occasional series on why ESPs need, or don’t need, lots of IP addresses to send mail properly. I need multiple IP addresses per customer so as to manage filtering issues Why this is right If you have, for example, three dedicated IP addresses per customer and one of those IP addresses gets “randomly” blacklisted, then you can divert traffic to the other two...
Number four of seven in our occasional series on why ESPs need, or don’t need, lots of IP addresses to send mail properly. I need multiple IP addresses per customer so that that customer can deliver mail in a timely manner Why this is right If your customer needs to deliver a message to 100,000 recipients within 30 minutes and 3% of them are at an ISP that only accepts 1000 emails per recipient...
Number three of seven in our occasional series on why ESPs need, or don’t need, lots of IP addresses to send mail properly. I need many IP addresses so that I can work around ISP throttling limits Why this is right: There are ISPs that limit the number of emails that can be sent from a particular IP address in a given time period to quite a low level, as low as 1000 emails per hour per IP address...
Number two of seven in our occasional series on why ESPs need, or don’t need, lots of IP addresses to send mail properly. I need lots of IP addresses so my MTAs can handle the volume of mail sent Why this is right One IP address per outbound smarthost is a sensible minimum. It is possible to set up multiple smarthosts behind a single IP address using a proxy server or reverse load balancer, and...
Number one of seven in our occasional series on why ESPs need, or don’t need, lots of IP addresses to send mail properly. I need at least one IP address per customer, to handle IP based reputation Why this is right While DKIM is gradually moving the main key for reputation tracking to a domain based token, right now the main key that is used to track reputation is the sending IP address. If...
In my last post I discussed the background as to why an ISP will require their users to use their IP address allocation efficiently. I also mentioned in passing that I’d discussed ESP address allocation with both ESPs and ISPs recently. The ESP was talking about assigning a couple of dozen IP addresses to each customer, because they might be useful for spreading load and it would provide...
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