IP/Domain Warmup

New IP addresses always look suspicious to Internet Services Providers (ISPs) until they establish a positive sender reputation. Several factors can influence the reputation of a new IP address, and it can take time to achieve maximum deliverability and avoid the spam folder. 

Infobip aims to ensure that you reach the highest possible email deliverability using IP/domain warmup. Once your domain reputation has increased enough to a reputable standard, you will be able to send campaigns with full deliverability. 

IP/domain warming is the process of methodically adding campaign volume week-over-week to a new IP Address to establish a positive sending reputation with Internet Services Providers (ISPs), and target engaged users at the same time. 

It is recommended that you start your campaign focused on your most reliable data around your subscribers, that it, your most engaged users. You can then add in your older data and less engaged users to later segments of the warmup. 

The goal during your warmup process is to send to subscribers who are least likely to complain and bounce. This would include those who have opted-in most recently and are consistent openers/clickers. 

During the warm-up phase, the more consistent you are with volume, frequency, complaint and bounce levels, the faster you will establish a positive sending reputation. If you send infrequently, anything less than weekly it will take more time to build a positive sender reputation. 

For every new domain used via the web interface, there will be an automated IP/domain warmup. If you are sending traffic via SMTP or HTTP API, you need to carry out a manual IP/domain warmup. 

To preserve the domain reputation while full operative sending, Infobip monitors traffic and bounce rates. If the bounce rate exceeds 5% of the total traffic over the last 24 hours, the service will be temporarily blocked. This ensures your reputation remains established and doesn’t portray a high bounce rate. 

Here are some pointers to ensure IP/domain warmup is done to the best of its ability and boosts deliverability: 

• Clean email databases by removing invalid emails 
• Only send emails to recipients who have signed up/opted in 
• Implement an email verification process during signup 
• Do not purchase lists on scrape sites 

You can read many more useful pointers in Deliverability Recommendations.

Automated Warmup 

Automatic Domain warmup is the process of increasing the sending speed (number of emails per day) of a domain to maintain the good reputation of a domain and IP address. 

Every newly registered domain that is added using the Infobip web interface is, by default, set to use automatic domain warmup, and sending speed restrictions are applied. This means that the domain can't send a large number of mails in a day, but if the domain sends regular traffic, then the automatic domain warmup service slowly increases the sending speed of the domain so that it reaches the per day mail target.

When you register a domain for setting up new marketing campaigns, the Warmup field shows the total number of emails that can be sent that day.

If your campaign is larger than the limit shown for that day, the remaining emails will be sent out the next day, whilst still conforming to daily limitations. 

Base Traffic

Base traffic is the maximum amount of emails sent by a particular sending domain in a daily (24-hour) window, calculated over the last 30 days. For example:

• If a domain sends 100 emails/day, then its base traffic is 100
• If a domain sends 200 emails/day and started sending 100 emails/day or less than 200, then its base traffic is 200
• If a domain sends 0 emails in the last 30 days, then its Base Traffic is 0

To protect the domain's reputation, if no emails are sent in the last 30 days, the warmup process must be restarted. 

Max Daily Traffic

The Max Daily Traffic value is set when you add or configure a new domain. You should set this value to be the amount of consistent traffic (emails/day) that you want to send from the domain.

This value also acts as a threshold to decide when a domain is considered to be warmed up. Whenever a domain's Base Traffic reaches two-thirds or more of the value of the Max Daily Traffic, then that sending domain is considered to be warmed up. All sending restrictions are removed until the base traffic remains at two-thirds or higher than the Max Daily Traffic.

For example, if you register a new domain for a campaign and want to send around 5000 emails in a day, with a customer base of 5000, configure the Max Daily Traffic as 5000.

When launching the first campaign of 5000, the sending speed will be 200 emails/day because the base traffic is 0. The following sending speed then applies:

• Campaign Day 1: Base traffic is 0, Sending Speed = 200/DAY (Default)
• Campaign Day 2: remaining emails to be sent 5000-200 = 4800, Base Traffic = 200, Sending Speed = 2X200 = 400/Day
• Campaign Day 3: remaining emails to be sent 4800-400 = 4400, Base Traffic = 400, Sending Speed = 2X400 = 800/Day
• Campaign Day 4: remaining emails to be sent 4400-800 = 3600, Base Traffic = 800, Sending Speed = 2X800 = 1600/Day
• Campaign Day 5: remaining emails to be sent 3600-1600 = 2000, Base Traffic = 1600, Sending Speed = 2X1600 = 3200/Day
• Campaign Day 6: remaining 0, Base Traffic = 2000 (because in last day 2000 emails sent, which is maximum in a day)

This campaign will finish and the domain will not be warmed up because it did not reach 3333 emails in a day. The Base Traffic is now 2000.

When a second campaign is launched, the sending speed will be 2X2000 = 4000/Day, and on day two of the second campaign, the domain will be warmed up because base traffic will be 4000 which is > 3333.

Sending Speed

The Sending Speed is the number of emails that can be sent in a day by a domain. It is usually 2 X Base Traffic (but depends on the warmup plan in our DB) if a domain is in warmup.

Key Points for Automatic Warmup

Here are some points to look out for when using automatic warmup:

• New domains always have a base traffic of 0 and an initial sending speed of 200/Day.
• Only one campaign from the sending domain is allowed at a time if the sending domain is on warmup.
• Warmup is not a one-time process but is a continuous process. At any point in time, a domain is considered warmed up or not based on the Base Traffic (if base traffic is two-thirds of  the Max Daily Traffic, then it is warmed up).
• Decrease in sending speed occurs in a scenario when a domain sends fewer emails on a consistent basis (for 30 days) compared to the sending speed on day 1. It will be reflected on the 31st day.

Manual Warmup (API) 

For traffic sent over the SMTP or HTTP API, you need to carry out a manual IP/domain warmup. The best way to ensure optimal email deliverability is to follow a simple 14-day warmup plan.

The following table suggests the volume of traffic for each day in the plan.

	Daily Volume
Day 1	200
Day 2	500
Day 3	1000
Day4	2000
Day 5	5000
Day 6	10,000
Day 7	20,000
Day 8	40,000
Day 9	100,000
Day 10	250,000
Day 11	500,000
Day 12	1,000,000
Day 13	2,000,000
Day 14	5,000,000

During the first 2 weeks, make sure that you target your most engaged subscribers. By week 3 and 4, target subscribers that have engaged within the last 60 days.

Do not target subscribers that have not opened or clicked emails within the last 90 days during the first 45 days of manual warmup.

If you find that you are warming more than 5,000,000, it is advised that you do not exceed this volume.