Email deliverability and domain reputation checklist for 2025

Imagine this – you’ve spent hours crafting the perfect email campaign, meticulously selecting the right words, designing eye-catching visuals, and including irresistible offers and critical information. You hit that deploy button, eagerly waiting for responses and conversions. However, instead your inbox remains eerily silent, and your delivery reports paint a disappointing picture of undelivered emails.

We can help you avoid this heartbreak. Drawing from years of experience working with global brands and small local businesses to improve their email deliverability, we have compiled a step-by-step checklist that you can use to achieve success with both your promotional campaigns and transactional emails.

A word of warning – while we can suggest quick fixes for specific deliverability issues, to achieve sustained and long term improvements may require an overhaul of your end-to-end process.

This why we have broken down the process into three key phases:

1. Email account setup
2. Onboarding – preparing to send
3. Executing email campaigns

Let’s start with the setup phase. If you already have a sender account you may be tempted to skip ahead, but we strongly recommend reviewing our suggestions. You may decide to start again.

1. Getting your email account set up right

When setting up your email account there are four critical considerations:

1. Selecting the right email service provider for your business profile
2. Your domain strategy
3. IP strategy – the type of IP address you will use
4. Authenticating the sender domain before sending emails

Select the right email provider

Choosing the right email service provider (ESP) is a critical decision and long-term commitment. To zero in on the right ESP, follow the below checklist:

• Test ESP performance: Put the ESP to the test with trial periods or pilot projects. Check for high deliverability rates (95-98%), fast delivery, user-friendly interface, easy integration, and robust reporting.
• Consider pricing plans: Review pricing structures and choose an ESP that fits your budget. Look for volume-based pricing options for high email volume to align costs with consumption.
• Evaluate deliverability support: Ensure the ESP offers excellent customer support and a dedicated email deliverability team. They should help troubleshoot, provide best practices, and maintain high inbox placement and sender reputation.
• Migrate email content and data: Transfer all email content, including templates and images, to the new ESP. Import bounce, complaint, and unsubscribe data as suppressed data to avoid emailing unsubscribed customers and protect your reputation.

Nail down your domain strategy

Once you’ve found the right email service provider for you, it’s time to have a look at your domain strategy. Domain strategy directly impacts your sender reputation and increases the chances of emails reaching recipients’ inboxes rather than their spam folders.

• Avoid corporate domains for bulk campaigns: Protect your sender’s reputation by using subdomains instead of your brand’s main domain for bulk emailing.
• Use different subdomains for different sending purposes: Maintain separate reputations by using different subdomains for various types of emails. This ensures that issues with one type of email won’t affect the deliverability of others. However, it is acceptable to use different local parts of the sender address for smaller volumes of emails. *See table below.
• Say no to cousin domains: Steer clear of cousin domains that deviate from your brand’s main domain. Stick to your brand identity and maintain consistency.
• Utilize “send behalf of” feature: If you must use the corporate domain as the “from-address,” use the “send behalf of” feature to send emails from a subdomain while displaying the corporate domain as the sender.
• Avoid brand-new domains as “from-address”: New domains lack a reputation with inbox providers, leading to potential deliverability issues. Choose domains with an established email sending history to increase deliverability and minimize spam filtering.
• Avoid the “no-reply” address if possible: Don’t trigger spam filters and reduce customer interactions by using “no-reply” as the local part of the sender’s email address. Opt for recognizable and readable addresses that encourage engagement.
• Don’t use parked domains as sender domains: Avoid using domains that are registered but not connected to any online service. Choose active and relevant domains to enhance your email campaigns’ effectiveness.

IP address strategy

The next step is to decide on your sender IP strategy.

There are two types of IPs to choose from – we will list the pros and cons of each and some of the criteria that you should consider when choosing.

1. Dedicated IPs

As the name implies, a dedicated IP is an IP address that’s exclusively yours and isn’t shared with other senders.

Considerations

• You send frequently (more than 3 times per week). If you stop sending emails for a few weeks, the ISP will treat you as a new sender, requiring domain warming.
• You send a minimum of 100,000 emails per month. A certain amount of sending is necessary to establish a solid reputation.
• Timely delivery is crucial for you. Example, for transactional emails a blocklisted shared IP won’t affect delivery time.
• You have time to warm-up dedicated IPs.
• You are prepared to pay a premium for dedicated IPs.

2. Shared IPs

Again, as the name implies, a shared IP is shared with other senders so everyone’s emails are sent from a single mail server.

Considerations

• You only send occasional campaigns.
• You send less than 100,000 emails per month.
• You don’t need to send time-critical emails.
• You want to get up and running quickly and have no time for IP warm up.
• Cost is a high priority

Domain authentication

The next step is to verify the legitimacy of your email sender ID and confirm you have the authority to use a specific domain name in the email address. This helps prevent email fraud, such as phishing scams and other types of email-based attacks.

Your domain authentication checklist

By following this checklist, you’ll ensure proper domain authentication, enhance email deliverability, and optimize your communication with recipients.

1. Implement DNS and authentication records during domain registration:

• SPF (Sender Policy Framework): Verify sender identity by authorizing sending servers for your domain.
• DKIM (DomainKeys Identified Mail): Add a digital signature to verify sender identity and message integrity.
• DMARC (Domain-based Message Authentication, Reporting, and Conformance): Provide instructions for handling failed authentication emails.
• MX (Mail Exchange): Specify authorized mail servers for receiving emails.

2. Verify all records using verification tools:

• Thoroughly verify records using reliable tools like Mr. Toolbox to identify and fix any issues promptly. 

3. Test configuration and deliverability with email testing tools:

• Use tools like Mail-Tester to test your configuration and check deliverability scores.
• Contact your ESP support if any issues need to be resolved. 

3. Register your domain in Google Postmaster Tools:

• Sign up for Google Postmaster Tools to monitor and optimize email delivery to Gmail users.
• Track domain reputation, spam rate, and email authentication to improve deliverability.
• Follow the setup steps on the official Google page or seek assistance from your ESP support. 

2. Onboarding

Domain warmup is crucial for ensuring email deliverability by gradually establishing a positive sending history and building trust with inbox providers, preventing emails from being marked as spam. 

Your domain warmup checklist

1. Follow warm-up plan and increase volume gradually:

• Implement a warmup plan – start with a small volume then gradually increase the number of emails sent over time to build trust and avoid spam filters

2. Target highly active recipients first:

• Focus on establishing positive engagement signals by prioritizing subscribers who recently engaged with emails or other channels. ISPs perceive active senders with valuable content as reliable.

3. Use a mixed ISP list for email traffic distribution:

• Diversify your recipient base to enhance deliverability by including subscribers from various ISPs (Gmail, Outlook, etc.). Building a positive reputation across multiple providers improves overall deliverability.

4. Maintain consistency in sending pattern:

• Establish a predictable pattern for ISPs and mailbox providers by being consistent with volume, frequency, and content.
• Build trust and credibility by avoiding sudden spikes or lulls in sending activity.

5. Use throttling techniques to increase volume-based on performance metrics:

• Analyze open rates, click-through rates, and spam complaints and then incrementally increase email volume based on positive performance indicators. This is the most effective way of scaling up email marketing efforts without negative consequences.

3. Email execution

During the execution phase of email campaigns, recipient list management, content optimization, and delivery monitoring take center stage as crucial elements to ensure optimal deliverability and engagement.

Recipient list management

Recipient list management is a crucial aspect of email marketing that involves maintaining a clean, engaged, and targeted audience to maximize deliverability and campaign performance. A well-managed list with a low bounce rate, low complaint rate, and high engagement signals to ISPs that you are a legitimate sender with quality content, so your chances of reaching inboxes are higher.

Here is an eight-step checklist to manage your email recipient list:

1. Don’t buy email contact lists: Instead, focus on organic list building strategies to cultivate a qualified and engaged audience. 
2. Use a double opt-in rather than single opt-in process: Implement a confirmation process to verify email addresses and reduce spam complaints. 
3. Regularly use email validation tools to clean mailing lists: Identify and remove invalid or risky email addresses from your list. 
4. Remove non-engaged/ inactive subscribers from the lists: Keep your list healthy by removing subscribers who haven’t shown activity or engagement. 
5. Make unsubscribe process simple: Provide an easy and accessible unsubscribe option to respect subscriber preferences. 
6. Segment email list based on subscriber behavior and interests: Deliver targeted and personalized content by dividing your list into distinct segments.
7. Allow subscribers to share their preferences: Involve subscribers in sharing their content preferences and email frequency.
8. Suppress bounces and spam complaints: Monitor bounce notifications, handle spam complaints promptly, and maintain a positive sender reputation. 

Content optimization

Optimizing the content of your email messages is crucial for improving email deliverability and avoiding spam filters.

Here’s a 13-point checklist to help you optimize your email content:

1. Use clear and compelling subject lines.
2. Avoid spam-triggering words and phrases.
3. Provide relevant, valuable, and personalized content.
4. Craft clear call-to-action (CTA) statements.
5. Include an unsubscribe option.
6. Use concise and scannable content format.
7. Ensure mobile optimization.
8. Avoid using too many images.
9. Use consistent design elements.
10. Avoid URL shorteners.
11. Optimize HTML and text versions.
12. Test and proofread your emails.
13. Comply with all legal requirements for your region.

Deliverability monitoring

Analyzing key metrics and monitoring your reputation is crucial to understand existing issues and make improvements.

Below is a checklist of metrics you should be checking regularly.

• Delivery rate: Infobip’s standard is 97%-99% 
• Bounce rate: ideally between or less than 2-3%   
• Open rate: from 15% to 25% for marketing emails, and 40-65% for transactional  
• Click-through rate (CTR): ideally between 2% and 5% 
• Click-to-open rate (CTOR): typically, between or greater than 20-30% 
• Unsubscribe rate: ideally below 1% 
• Spam complaints: ideally less than 0.2%. 

Engagement metrics like clicks, opens, and CTOR (Click-to-Open Rate) impact sender reputation and email deliverability. High engagement indicates value to subscribers and improves inbox placement, while sudden fluctuations in these metrics can indicate reputation issues that need resolution with your ESP. 

Check Google Postmaster and monitor reports daily

Google Postmaster Tools is a free service provided by Google that helps email senders and administrators monitor and improve their email deliverability to Gmail users. The service provides valuable insights about deliverability and includes reports about:

IP Reputation: How Gmail’s spam filters view your IP address and domain reputation.

Authentication: Indicates if you have properly set up SPF, DKIM, and DMARC for email authentication to stop spammers and phishers from using a domain they don’t have a right to.

Encryption: Shows whether the sender has properly configured Transport Layer Security (TLS) encryption to protect email in transit.

Delivery Errors: Highlights any errors encountered in delivering your email messages.

Monitor SNDS reports with your ESP

SNDS (Smart Network Data Services) is a free reporting tool provided by Microsoft that helps monitor email senders and improve their email deliverability to Outlook and other Microsoft email services. Request your ESP`s expertise to provide you with valuable insights and metrics on email delivery, including: 

• Complaints: show how many users have marked the sender’s emails as spam or junk. 
• Spam trap hits: shows whether the sender has sent emails to inactive email addresses or known spam traps. 
• Volume: shows the number of emails sent to Microsoft email services. 
• Sender reputation: shows how Microsoft’s spam filters view the sender’s IP address and domain reputation. 

Check whether your IP/domain is blocklisted

Regularly check if your domain or IP address has been blocked. Utilize reputable online blocklist checking services to ensure your emails are not being flagged as spam. If you are listed somewhere, try to get delisted. Some sites where you can check this are:

• Mx Toolbox
• Hetrix Tools
• Bulk Black List
• Multirbl

Monitor inbox placement

Use these tools to check if emails are in the Inbox or spam folder:

• Glock Apps
• Validity
• Return Path

Achieving and maintaining industry-beating email delivery rates is crucial for the success of email campaigns. By following our checklists and implementing our recommended strategies, you are well on the way to success with a channel that is still regarded by all generations as the most important for B2C communication.