When sending emails to customers, many things can go wrong. Email addresses get entered incorrectly at signup. ISPs can block an IP address even when you have a great reputation. Multiple complaints from recipients can ruin a good reputation in a short amount of time. Unfortunately, these are all very common problems that affect the viability of your program when you focus on quantity instead of quality at the expense of deliverability. Fortunately, a special procedure known as the “warm-up strategy” can help. Here’s how.
Why IPs Get Blocked in the First Place
The most common reason ISPs block IP addresses is that they have a poor reputation. ISP spam filters work by checking an email’s header and body for keywords, such as “Fast Cash” or “Credit Cards,” which indicate that the sender is likely to send spam. This can happen even if your company has a good reputation elsewhere – if one of your emails goes out to just the wrong person at the wrong time, it could end up on the blacklist and cause all of your other emails to be blocked as well.
Another reason why ISPs block IPs is that recipients have complained about receiving too many emails from them (or from one particular sender). Spam complaints are often made directly to an ISP when someone receives an unsolicited email or feels like they are being harassed by marketers trying to sell them something; sometimes, people will even make false claims against companies just because they don’t like what they do! Whatever the reasons may be behind these complaints, when enough people file one against you, then it becomes harder for you to send future messages through their network, since those messages would come with an inherent risk of being caught in filters simply based on who sent them out before (even if you were sending legitimate messages).
How to Boost Your Sender Reputation
The reasons discussed above is why it’s essential to establish your sender reputation when you first start emailing contacts. We call this process IP address warm-up, and it is one of the most important steps in any email marketing plan. Building a good reputation with ISPs takes time and effort, but it is worth the investment.
When you send your first batch of emails, ISPs will see that IP address is sending spam and block it. To prevent this from happening, you need to establish a sender reputation. We call this process IP address warm-up, and it is one of the most important steps in any email marketing plan.
The Warm-Up Strategy for IP Reputation & Email Sending
An IP warm-up strategy is the process of gradually increasing email send volume on a new or inactive dedicated IP to establish a positive sender reputation with mailbox providers like Gmail and Outlook. The goal is to demonstrate consistent, legitimate sending behaviour by starting with small volumes and targeting only highly engaged recipients. Proper authentication (SPF, DKIM, and DMARC), clean opt-in lists, and predictable sending patterns are essential foundations before any warm-up begins.
During the warm-up period, send emails daily at consistent times and slowly scale volume based on performance, expanding audiences only after engagement remains strong and complaints stay low. Monitoring key metrics—such as open rates, bounce rates, and spam complaints—allows senders to pause or slow growth if issues arise. A disciplined warm-up typically takes two to four weeks but is critical for long-term inbox placement and sustainable email performance.
How to Put it Into Action
Building a good reputation with ISPs takes time and effort, but it is worth the investment. That said, there are some ways you can speed up the process. Here’s where the warm-up strategy comes in.
Several factors contribute to your sender reputation, including engagement rates, spam reports and bounce rates. A lot of businesses make mistakes when sending emails to their contact, this may result in poor engagement and delivery issues. For example, sending too many emails at once or sending too many emails in a short period of time (like over a week). These tactics hurt your IP address’s reputation because ISPs see them as reckless behaviour for sending emails to subscribers who aren’t engaged with your content or may not be real subscribers at all.
Here are some tips for keeping your reputation clean:
- Start with a clean IP address. Make sure you have an IP reputation that’s in good standing before you start sending emails.
- Limit the number of sends you send in a short period of time to new subscribers or those who haven’t engaged with your content. ISPs look at these kinds of behaviors as reckless and may block your IP address from sending emails altogether if they see it happening too often or over an extended period of time.
- Check feedback from customers regularly so you can improve engagement rates, which will also help increase opt-ins and reduce spam complaints.
- Keep bounce rates low by ensuring that unsubscribes are removed from lists immediately after they occur (or manually removing them yourself).
- Contact the Digital team at Mixto and relax, they will take care of your project from start to end.
You don’t have to be a data scientist to make your emails hit their mark.
Let Mixto Help You With Safe-Sender Email Marketing
With Mixto’s digital services platform- MIO, you can get the most out of your email marketing campaigns with ease. We offer a range of digital services that are tailored to help you achieve your goals, including:
- IP warm up (getting the most out of your IPs)
- Mass emails (mass emailing as a service)
- Digital email packages (including design, copywriting, and delivery)
- Password protected attachments (high security custom passwords)
- Template based emails (lets you create great looking emails quickly and easily)
- 24/7 run time with batch scheduling
- Delivery right inside the inbox where they are supposed to be.
