Sender Reputation Building or Warming up your IPsIn the world of email deliverability, technologies and methodologies are in a constant state of flux. ISPs have to be on the alert for new spam and virus attacks, and as a result are constantly changing their blocking and filtering technologies to combat these problems and to protect their customers. When it comes to delivering email to the Inbox, ISPs also have to be careful about what email they accept, especially regarding senders from which they have never seen email traffic.

A classic example of this is where a company may start with or switch to a different Email Service Provider, and as a result will be sending their email from a brand new IP address. From an ISP’s perspective, this is like “the new kid on the block” – they’ve never seen email traffic coming from this new IP address. They don’t know if these messages are legitimate or simply a spammer that has decided to switch IP addresses. Thus, they are going to be very cautious about the email coming from that new IP address, and will scrutinize it with the full extent of their spam filters until they can ascertain what kind of email is being sent and its impact on their network. If the messages sent generate complaints or high amounts of hard bounces, the ISP will most likely not remove these filters and may opt to bulk and/or block those messages altogether. However, if the messages don’t generate complaints, and are sent to valid email accounts, the ISP will most likely turn down their filters and let email pass through more easily. By the very nature of sending from a new IP address, the sender is building either a good or bad reputation with that ISP.

There is also a volume factor related to building a good sending reputation. Using the above example, if a sender using a brand new IP address, sends to their entire subscriber database, depending on the size of the list, the ISP could see this as a flood of potential spam emails (legitimate or not) and would again use the maximum amount of filtering against them. The sender has then effectively shot themselves in the foot by establishing a bad sending reputation on their first send.

So the question remains – how do you let an ISP know that you, as a sender are legitimate? Again, from their perspective, a sender sending from a new IP address has built no reputation, or could even start with a negative reputation. It is therefore the sender’s responsibility to build that relationship, and establish a good sending reputation. Here is how this is accomplished:

1. Don’t send spam

    Use the best practices that have been discussed on my past blogs:

    1. Validate email signups
    2. Send relevant content
    3. Give full disclosure to the subscriber about what they are receiving

2. Don’t send to your entire list at once

    If you have a list of 200,000 subscribers, which almost always will contain old or invalid emails on it, don’t send to the entire thing at once. Break it up into smaller “chunks”. Give the ISPs a chance to see the types of messages that are coming, and let them establish a sending reputation. Here’s a suggested model to follow:

    Sample message volume: 200,000
    First send: 2000 or 1%
    Second send: 10,000 or 5%
    Third send: 20,000 or 10%
    Fourth send: 40,000 or 20%
    Fifth send: 80,000 or 40%
    Sixth send: remaining

If you give the ISPs a chance to get to know you and the type(s) of email you are sending, it will give them a chance to gradually establish a sender reputation for you, which will inevitably be to your advantage.

Until next time,

Drink Responsibly, Drive Responsibly, Email Responsibly

Jaren Angerbauer
Director of Deliverability