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How to Warm-up your IP Address Efficiently for Getting the Best Results in Email Marketing

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, 101.134.129.235 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 important for an Email Marketer

For an Email Marketer, the sender reputation is directly linked to their IP Address. It is imperative that as the sending reputation determines the delivery rates of the marketing emails and their inbox placements, the IP address is of utmost importance for the success of the email marketing campaigns and hence to the email marketer. 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 positives of the warming up process are that you have a clean slate to start with. The previous sender 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 in the sender 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 build some history on the new IP address.

Luckily, 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 reputation is a moving target. It is calculated over a period of 30 days. So, even if your sender reputation is on the lower side, you can always enhance 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 the warming up process in the following cases:

  • When using a shared IP address, the warming up process is not required. The reason is that the users already using the IP address have already warmed up the IP address for you to use it instantly.
  • 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), 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 create 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 are 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 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 analyse the email quality being sent in the meantime. The emails are analysed 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 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 address can be removed and send your emails gradually over a period of time. Performing such favourable actions will lead your ISPs to trust your emails, thus enhancing your sender reputation.

How to go about the warm up process

Generally, ISPs have daily sending allowance for email senders. Try exceeding it and the excess emails will be blocked by the ISPs. This phenomena is called “throttling” or “deferral”. This is different from a hard bounce which happens because of 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 that you 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 on a daily basis. 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.

How do I setup my warm up sending plan?

Since you understand that IP warm up is important for your bulk mailing success, you can optimize a 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 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 increase 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.

Above schedule is recommended by us based on production and test data analysis of our 3200 dedicated IP behavious, however there are also alternative warming up methods that are commonly 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.
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 total monthly volume by 30 days, divide it by 15 days.
Example: You have 60,000 email/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 highest engagements 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 warm up period and in the long run, it is always better to be a good sender. 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
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