Warming Up Your IP Addresses Automatically

September 7th, 2021

When sending email messages, there are many best practices for ensuring optimal deliverability. One very important factor in deliverability is IP reputation. However, when using a brand new server and IP address, how can you build a good reputation? In this article, we will explain how to warm up an IP address in a way that will build a good reputation and improve email deliverability.

warm up ip address

What Is IP Reputation?

Good reputation: If a server is known to send lots of good quality emails (messages that people do not consider spam-like), then the server’s IP address is looked on favorably by ISPs (such as Yahoo!, Google, Microsoft, etc.). Having a good reputation allows organizations to send large quantities of good emails that will be delivered to recipients. A server with a good reputation has an IP address that we call “warm” (think warmed up and humming along).

Bad reputation: If a server is known to send junk or malicious emails (according to the recipients of the email), then many ISPs will throttle the emails, accepting only a few messages at a time. They may even flag emails as spam and not deliver them. A server with a poor reputation will need work to repair it.

No reputation: A new server may not have a recent history of sending emails. As a result, the IP address may have “no reputation.” ISPs are very skeptical about emails from servers with no reputation or without evidence of good email sending. A typical sign of a spammer is when a server with little or no reputation suddenly starts sending large quantities of email. ISPs will detect this and quickly throttle or block such servers, moving them from “no reputation” to “bad reputation.”

Warm Up an IP Address from No Reputation

So, you have a new dedicated server and want to start sending a lot of email. The new dedicated server’s IP address is likely to have no reputation, so what can you do to warm it up? More importantly, how do you go from having “no reputation” to a “good reputation?”

The IP address must be warmed up to achieve a good reputation. This process involves the following steps:

  1. Start by sending slowly. Send less than 50 email messages per hour in the beginning.
  2. Each day, send more messages.
  3. Over the course of about one month, ramp up to the full sending rate.
  4. Start sending to email lists that have clearly opted in to receiving emails. This helps ensure that the recipients will not mark it as spam or flagged it as unwanted.
  5. Follow all of the other normal best practices for good email delivery (e.g., good content, good lists, SPF and DKIM records in place, etc.)

Following this warm-up process makes it possible to reach a full sending rate in a reasonable amount of time without being penalized for sending too much too soon.

Many people are anxious to get that first huge email blast off ASAP, but unless the IP address is adequately warmed up, those messages won’t land in the recipients’ inboxes. Furthermore, the server’s reputation will be damaged and will take longer to recover and properly warm up.

Email throttling and manual IP warm up

If the email sending program has sending rate throttling built-in, it can be used to ramp up sending slowly. However, many sending systems do not know how to limit email sending correctly. For these cases, LuxSci has an email throttling feature in the server status and configuration page (Existing customers can go to the servers page, click on your server, and scroll down to the “Email Queues” section of the Server Vital Signs widget).

When “email throttling” is enabled:

  • Emails can be sent to the server as often as desired.
  • The server will queue these messages.
  • The server will send them out based on a specified “email throttling” rate.

For example, if the rate is 1,000 messages/hour and 24,000 messages are sent, they will be queued and sent out evenly over 24 hours. The first messages received are the first ones sent out.

The throttling rate can be changed as desired to manually warm up an IP address and fix problems with tarnished IP reputation.


  1. The actual maximum rate at which a server can send email is a function of many factors, including the power of the server and the nature of the messages sent. See Sending Rates for more details.
  2. No matter what the configured maximum sending rate is, the excess messages will be rejected if sending emails to more recipients in a month than the overall monthly recipient limit.

Automatic IP Warm Up

LuxSci’s Automatic IP Warm Up is usually a good alternative for those with new servers as it eliminates all manual work and decision-making and takes care of the warm up process. Customers can go to the server status and configuration page, enable “Automatic IP Warm Up,” and leave “Email Throttling” set to “0” or “-1” (the default, which means “no specific throttling”). Then:

  1. LuxSci enables email throttling and sets the rate limit for today to be very small: 20 messages/hour.
  2. Each night, LuxSci increases the allowed sending rate (see the table below for the schedule) once the current rate for the entire day is met.

Customers going through the automatic IP warm up process need to:

  1. Actually send messages. If emails are not being sent, the warm up will not impact IP reputation and the rate limit will not automatically increase.
  2. Send enough messages. It’s essential to send enough email, so the server mostly sends at close to its maximum allowed rate during the first weeks. In this way, IPs out there see the server progressively sending more and more emails. We usually recommend sending a good size email blast in the beginning and allow that to slowly work its way through the recipients as the IP warms up and the sending rate increases.
  3. Use best practices. As we have said before, the messages must have good content, do not look spammy, and are sent to recipients that actually want to receive emails (i.e., they are unlikely to mark it as spam). The goal is to validate the server’s reputation by sending more and more good email to willing recipients. By not following this advice, the warm up process may leave you with a bad reputation.

Automatic IP Warm Up Schedule

The following schedule is used for setting the server’s sending rate during the automatic IP warm up period. A day-to-day ramp-up progression assumes that as much mail is sent as possible as rate-limiting allows. If less than 90% of rate-allowed messages are sent during 24 hours, the rate will not automatically increase to the next level. This helps make sure that the warm up is actually effective.


DAY Rate: messages/hour Maximum messages/day Total maximum messages sent
1 (Week 1) 20 480 480
2 30 720 1,200
3 40 960 2,160
4 55 1,320 3,480
5 75 1,800 5,280
6 110 2,640 7,920
7 150 3,600 11,520
8 (Week 2) 210 5,040 16,560
9 300 7,200 23,760
10 420 10,080 33,840
11 580 13,920 47,760
12 800 19,200 66,960
13 1,000 24,000 90,960
14 1,600 38,400 129,360
15 (Week 3) 2,250 54,000 183,360
16 3,100 74,400 257,760
17 4,500 108,000 365,760
18 6,000 144,000 509,760
19 8,500 204,000 713,760
20 12,000 288,000 1,001,760
21 17,000 408,000 1,409,760
22 (Week 4) 23,000 552,000 1,961,760
23 33,000 792,000 2,753,760
24 46,000 1,104,000 3,857,760
25 64,000 1,536,000 5,393,760
26 90,000 2,160,000 7,553,760
27 126,000 3,024,000 10,577,760
28 175,000 4,200,000 14,777,760
29 (Week 5) 245,000 5,800,000 20,577,760
30 345,000 8,280,000 28,857,760
31 480,000 11,520,000 40,377,760
32 675,000 16,200,000 56,577,760
33 950,000 22,800,000 79,377,760
34 1,250,000 30,000,000 109,377,760
35 1,800,000 43,200,000 152,577,760


For example, if you wanted to warm up your server so that you could send 30,000 messages in one day, you would need to warm up for 14 days and send to at least 90,960 recipients during that warm up period to progress through those first 14 levels of sending.

If you are interested but would like more information to help choose your optimal server/cluster capacity and optimize your warm up process, request a Free Consultation.