How to Warm up an IP Address – Clearalist Bulk Email Verifier

What is an IP Address?

An IP Address is a pattern of four numbers separated by three dots between them. The pattern is like: abc.def.ghi.jkl. For example, is an IP address. Each number in an IP address can range from 0 to 255. An IP address identifies a computer (read device) connected to a computer network. IP Address stands for Internet Protocol Address.



Why IP Addresses are essential for an Email Marketer

For an Email Marketer, the sender’s reputation is straight linked to their IP Address. It is important because, as the sending reputation defines the delivery rates of the marketing emails and their inbox placements, the IP address is of absolute importance for the success of the email marketing campaigns and hence to the email marketers. This is the reason why email marketers opt for a dedicated IP address as against a shared IP address. On a shared IP address, your reputation can only be as good as the reputation of the worst sender in the group.


Pros and cons of the warming up process for a new IP address

The benefit of the IP warm-up process is that you have a clean slate to start with. The earlier sender’s reputation does not matter. There is an opportunity to enhance your sender reputation with the ISPs (Internet Service Providers) with the correct warming-up process. The other positive is that, for the new IP address, it is easy to “not” act like a spammer. The ISPs will guide you by sending warning messages if you are doing something wrong. This way, you can correct your email sending practices before any harm is done to the sender’s reputation. And those good email sending practices will help you maintain that good sender reputation in the long run.

The negatives of the warming-up process are that due to the lack of any sending history, your ISPs will not recognize you anymore. They will treat you like any other sender (read spammer) unless you develop some history on the new IP address.

Fortunately, it doesn’t take long to create some history on the new IP address. 15 days to a month is usually long enough for the purpose. Also, it is worth noting that the sender’s reputation is a moving target. It is calculated over 30 days. So, even if your sender reputation is on the lower side, you can always improve the parameter following good email sending practices. On the other side, even if you have an enhanced parameter, you can always degrade it by following bad email sending practices.


Can the warming-up process be avoided?

We can avoid warming up the process in the following cases:

  • When using a shared IP address, the warming-up process is not needed. The reason is that the users already using the IP address have already warmed up the IP address for you to use it immediately.
  • If your sending volumes are low (less than 100,000 emails per month), IP address warming up is not required. This is because the ISPs will usually not notice the lower email volumes.
  • If you are using the IP address for sending emails (that means the IP address is not a new one) and the emails are sent regularly (at least once a month), the warming up process is not required for such an IP address.


The sender reputation calculation process

A new IP address will not have any sender reputation as such (due to lack of any sending history). As such, the IP address needs to build a fresh reputation with the ISPs. The ISPs will only allow bulk emails to be sent to the recipient’s inboxes once they are sure that the IP address that is sending the emails is sending relevant, useful, and permission-based emails to their subscribers.

ISPs use complex algorithms to analyze the quality of the emails being sent. Based on this analysis, the sender’s reputation for a particular IP address is determined. To ensure better deliverability of emails to the recipient’s inboxes, it is recommended to start the email sending process slowly and increase the email volume gradually over time so that the ISPs can analyze the email quality being sent in the meantime. The emails are analyzed based on the below-mentioned factors:

• Spam Complaint

• Bounces

• Opens

• Clicks

• Non-existent email address

• Unsubscribe rate

• Emails saved (in permanent folders)

• Emails forwarded

Whenever an ISP notices a new (dormant or cold) IP address suddenly sending emails, they will start their email evaluation process for the traffic coming from that particular IP address. Since volume is the most important factor for the ISP’s spam filters, it is best to start with a low email volume and gradually build up the volume, allowing the ISPs to evaluate the email quality by the way the recipients treat your emails.

To enhance your sender reputation during the warm-up process (and in long term), ensure that the recipients are getting emails they want to read, perform list management so that bounces and non-existent email addresses can be removed, and send your emails gradually over some time. Performing such favorable actions will lead your ISPs to trust your emails, thus enhancing your sender reputation.


How to implement the warm-up process?

Generally, ISPs have a daily sending allowance for email senders. Try exceeding it and the excess emails will be blocked by the ISPs. This phenomenon is called “throttling” or “deferral”. This is different from a hard bounce which happens because of a non-existent or wrong email address. But as the ISPs come to trust your emails, they will gradually relax the daily email sending capacity. In the warm-up period, your email volumes need to conform to those email sending allowances by the ISPs so that throttling can be avoided.

Moreover, ISPs normally send back failure mails in case your emails could not be delivered. Keep an eye for such delivery failure messages and adjust your email volumes to conform to such messages for each ISP. Also, it is important to sent consistent email volumes to different ISPs. For example, if you send 10 emails to one ISP today and 1000 emails to the same ISP tomorrow, the ISP will issue a red flag to the IP address and throttling, accompanied by the delivery failure messages would result from the ISP end.

During the warm-up process, check your email delivery-related data daily. These parameters should be considered for the same:

  • Email delivery rate
  • Inbox placement rate
  • Bounce rate (both hard and soft)
  • Open rate
  • Click rate
  • Unsubscribe rate
  • Spam complaint rate

Moreover, it is important to categorize these data according to the ISP, campaign, day of the week, time of the day, email volume, type of email (transactional or bulk emails), etc.


What is Email Marketing?

How do I set up my warm-up sending plan?

Since you understand that IP warms up is important for your bulk mailing success, you can optimize an email sending schedule and highly recommend that you follow it during the first few weeks of mailing to subscribers.

Sample breakdown of that you should be sending daily during the first 12 days:

– 400 Yahoo addresses

– 400 Gmail addresses

– 500 Hotmail addresses

– 600 AOL addresses

– 1,000 other ESPs

TOTAL: 2,900 subscribers

The day-by-day schedule should have the following shape:

DAY 1: Email sent to ~ 2,900 subscribers

DAY 2: Email sent to ~ 5,800 subscribers

DAY 3: Email sent to ~ 8,700 subscribers

DAY 4: Email sent to ~ 11,600 subscribers

DAY 5: Email sent to ~ 15,000 subscribers

DAY 6: Email sent to ~ 20,000 subscribers

DAY 7: Email sent to ~ 25,000 subscribers

DAY 8: Email sent to ~ 30,000 subscribers

DAY 9: Email sent to ~ 45,000 subscribers

DAY 10: Email sent to ~ 60,000 subscribers

DAY 11: Email sent to ~ 80,000 subscribers

DAY 12: Email sent to ~ 100,000 subscribers

Along with the schedule you also need to throttle the number of emails evenly over the day instead of sending them all as quickly as you can.

You need to gradually raise your outbound email traffic from about 1,000 emails/hour (at the outset) up to 10-20,000 emails/hour when the process is complete.

The above schedule is recommended by us based on production and test data analysis of our 3200 dedicated IP behavior, however, there are also alternative warming up methods that are usually used like:

Conservative Approach:

Estimate your total monthly email volume and divide them by 30 and then spread your sending evenly over the first 30 days.

For example: if you will send 60,000 emails/month, you should start off sending 2,000 per day over the initial first month.

Aggressive Approach:

Instead of dividing the total monthly volume by 30 days, divide it by 15 days.

Example: You have 60,000 emails/month but you need the emails to reach your recipients in half as long of a time frame, send 6,000 per day for the first 15 days.

Since the highest engagement rates are required for better sender reputation during the warm-up period, transactional emails are the best choice and they have the highest open and engagement rates. Welcome emails too are a good choice. During the warm-up period and in the long run, it is always better to be a good sender. The following points would help in achieving the same:

  • Respect your subscribers
  • Send relevant emails to your subscribers
  • Send useful emails to your subscribers
  • Keep your email list clean
  • Honour unsubscribe requests from your subscribers
  • Avoid spamming
  • Send emails only to your subscribers who have opted-in


No email list is perfect. Even if you’ve built it up yourself, there will still be undeliverable addresses. People mistype their email address when filling out your opt-in form. Or, they deactivate an email account or allow it to fill up such that it can’t receive any more messages.

No matter what type of business you’re running or how you’ve put together your email list, using an email verification service like Clearalist is far and away from your best bet for reducing your bounce rate.

With email verification, you’ll know in advance which addresses are undeliverable, and you can remove them from your list before you send out your next email.

Cleaning your list usually should be a routine task if you want to maximize your delivery rate.

By understanding the importance of email delivery rate, using an opt-in system, and verifying your email list with Clearalist, you’ll be on your way to low bounce rates–which means more clicks, and more conversions.


Happy Mailing guys!! 😊