Warming up an IP address

Sending a large number of emails immediately from a fresh new IP address, can get you deferred or blocked by ISPs such as outlook.com, gmail.com. This is mostly because a new IP does not have a reputation score since email has not been sent from it yet. The reputation score is an indication of the trustworthiness of an email sender’s IP address and is used by email providers and filters to determine additional email filtering criteria.

One way to improve your reputation score, is to warm up your IP address. This involves ramping up email volume over a specified period of time. Once you have warmed up your IP address succesfully, you can send large numbers of emails and get through the ISP's killer filters with more success.

How to begin? Peter will show you how to start sending emails over a new IP address without delivery failures.

Why warming up an IP address is important

An IP that has not sent any emails yet does not have a reputation score. A new IP is considered 'cold'. And a good reputation score is not achieved overnight. You need to start small and gradually increase the number of emails to send larger volumes in the end. Your reputation increases as more recipients open your email, and the ISPs will begin to accept more email from your IP address because of the increasing reputation.

Do I need to warm up my IP address?

If you are a small sender, around 10,000 or less emails per month, you will most likely stay below the radar of ISPs. Then, there is no need to warm up an IP. But if you send more than 10,000 emails a month, you should consider warming up your IP address.

First things first...

Great, now that you know if you have to warm up or not, there are a few things you need to check first.

• Ensure key email authentication methods (SPF, DKIM and DMARC) are in place
• Start sending only to recipients that have recently opened or clicked an email
• Avoid sending emails to recipients that have 'hard-bounced' in the past
• Regularly monitor your email deliverability (bounce rate < 10% & complaint rate < 0.1%)

Ramping up guide

As mentioned before, warming up an IP involves ramping up email volume over a specified period of time. Please be aware that every sender is different and so is every ISP. How many emails you send in that first period depends on the amount of emails you want to send once the warming up process is finished.

A good rule of thumb for larger ramp-ups is to start your sending at 10,000 prospects per day. Assuming your bounce rate stays below 10% and your spam complaint rate stays below 0.1%.

For example, if you want to send 1,000,000 emails a week, you should ramp up like this:

Week	Emails per day	Emails per week
1	10k per day (5 days)	50k
2	20k per day (5 days)	100k
3	40k per day (5 days)	200k
4	80k per day (4 days)	320k
5	160k per day (4 days)	640k
6	250k per day (4 days)	1M
7	333k per day ( 3 days	1M
8	500k per day (2 days)	1M
9	1M per day (1 day)	1M