High email deliverability depends on coming up with the correct processes and implementing them with disciplined habits. Below are six ways to stay out of the spam folder.
Watch your sender reputation and email performance like a hawk. These are the things that determine and show how many of your recipients are getting your messages. Email monitoring is a broad topic, and it’s easy to get lost in the weeds, so here I’ll introduce you to the most important types of monitoring and provide a concrete suggestion of what you can do for each one.
1. Reputation and Deliverability Monitoring
Your reputation is your email credit score. It aggregates all your email sending activities over time. The lower your reputation, the more of your emails end their lives in someone’s spam filter. Just like your credit score, many different entities track and compile your email sending reputation. So, monitoring your sender reputation is tricky because there are several places to look. Additionally, while your email addresses contain a domain name (e.g., example.com), the chance a particular email ends up in spam can depend on the specific IP address (e.g., 64.233.160.121) the email originates from, not just the domain name it came from.
However, there is one tool provided by the single most popular Email Service Provider, Gmail. About half (~45%) of your recipients use Gmail, and viewing the results from this tool is probably the single most important thing you can do for your email health. You can check your email reputation according to Gmail using Postmaster Tools.
Postmaster Tools will tell you if your domain has a High, Medium, Low, or Bad reputation. It is up to you to increase your reputation, and if it drops, to figure out why. Do note that Postmaster Tools is only going to show results if you send, on average, about 100 emails a day or more. As with most other things Google, this limit is not published by Google anywhere, but the 100 emails a day threshold lines up with our experiences.
You will need some technical help or knowledge to set up Postmaster Tools.
- Head on over to https://gmail.com/postmaster/
- Click “Get Started”, and follow the instructions
- Add the domain you are sending your campaigns from (e.g. example.com or marking.example.com, whatever the case is).
- Verify ownership of the domain by adding a TXT record to your DNS.
Once you verify your domain, you’ll be able to see your domain sender reputation per Gmail for the last 120 days. If you don’t see any data, you are probably not sending enough emails to get onto Google’s radar.
It can be a drag to remember to check Postmaster Tools every few days, so if you want to be notified of changes to your domain reputation group, then you can use GlockApps’ Postmaster Tools integration and set up alerts when metrics change. GlockApps is an email deliverability testing and insights tool that we’ll cover in more depth later.
In addition to looking at Gmail’s opinion of your emails, you should also make sure your not on any email blacklists.
2. Blacklist & IP/Domain Health Monitoring
If you end up on a blacklist, then your emails might never even reach your recipients’ mailboxes at all, inbox or spam.
There are dozens and dozens of places to check your email domain health and blacklist status. Instead of listing them all here, I’d like to suggest just one. MxToolbox is a multifaceted resource that offers much more than just domain checks. It’s a high-quality service that is worthwhile to get familiar with. So, to check if you’re blacklisted and to see what your overall domain health is, I suggest you use MxToolbox’s free tool, the Email Health Report.
The report is fast and accurate. Note that if you don’t have a dedicated IP and are using an email provider like Gmail, you’ll get a warning that reverse DNS does not match the SMTP banner. Unless you want to spring for a dedicated IP (or want to try talking Gmail into changing their Pointer (PTR) record just for you), you can ignore that warning. Ultimately, the crucial thing is to set up your MX and SPF records correctly. You don’t necessarily need to have PTR records when using Gmail.
3. Inbox Placement and Spam Monitoring
All of the previous monitoring has been pretty general. Inbox placement and spam monitoring look at real-time deliverability for specific email addresses.
There are many paid services for looking at inbox monitoring, but I’m going to suggest a simple, highly effective, free alternative.
If looking for your own solution, make sure you find one where you have to send emails to multiple addresses for a realistic test. Sending one email to one address does not provide enough information to assess the situation.
Mailreach has a free tool to check what percentage of your email campaigns are going to spam. Go to https://www.mailreach.co/email-spam-test, and you’ll get a list of real email addresses to send to. You can send via Gmail, HubSpot, Sendgrid, whatever. Once you send out your email to the list of recipients, Mailreach will track for each recipient whether the message goes to their inbox or spam.
It’s very important to do an inbox placement test with your campaign sending address at least once a month. The more emails you send, the more often you should test.
There are many paid inbox placement and spam monitoring tests. If you set up Postmater Tools integration with GlockApps, they also have spam monitoring. You get a few free ones when you sign up, and then you have to pay for them.
4. List Health and Engagement Monitoring
Monitoring reputation, deliverability, blacklists, IP/domain health, and inbox placement will tell you a lot about your emails, but what about your audience? You have to pay attention to your recipients, too.
You should only send emails to those likely to engage with them, and you should track engagement. Encourage clicks on your email while discouraging marking your emails as spam via email clients. If you make it easy for people to unsubscribe, they will unsubscribe instead of marking your email spam. If people mark your email as spam, then all your other emails will be more likely to get sent straight to spam by email service providers (ESPs). This is why, counterintuitively perhaps, you should make it extremely easy to unsubscribe. Also, if people do not engage with your emails ESPs are more likely to mark them as spam.
There are numerous paid list cleaning services. Since we use HubSpot, and so do many of our clients, I’ll focus on that. Any service is going to have very similar metrics it follows. These will be the metrics that matter for ESPs like opens, clicks, unsubscribes, and spam complaints.
To access HubSpot’s built-in email health monitor:
- Go to Marketing
- Select Email
- And click on the Health tab.
HubSpot ranks your email health from Poor to Excellent using a numeric scale from 1 to 10. You should aim for 7 or higher (good) and definitely keep above 4.
The HubSpot report is much more actionable than the previous tools we covered. They’ll list your best and worst performing emails as well as the top recommendations for you. Review the data and try to increase opens and click-throughs (clicks on links in your emails) while decreasing spam reports and hard bounces.
Below is a quick checklist of how to keep your email lists healthy:
- Always, always, always only send emails to people who have opted in. Opt-in means that someone gave your website their email address directly with the understanding that you will send them marketing emails. That is, you didn’t buy their email address or grab it from a support or other interaction where a marketing follow up is not expected. Prefer explicit consent to implicit consent. The best is to use double opt in. Double opt in works by someone first signing up via a form, and then clicking a confirmation in an email follow up.
- Increase positive engagement (opens, clicks)
- Make it easy to unsubscribe. You don’t want people using their email provider’s unsubscribe button.
- Decrease negative engagement (bounces, getting flagged as spam)
- Prune your list every 3–6 months. Remove inactive or unengaged subscribers.
- Segment your lists. Don’t blast everyone; send only to people most likely to open a specific email. A good benchmark: at least 30% of your list should have engaged in the past 6 months.
5. Authentication and Domain Monitoring
Take the time to properly authenticate your emails with SPF, DMARC, and DKIM. Things change, so make sure you validate your settings at least once a quarter. For example, you might stop using an email service or start using a new one. If you forget to update your SPF, a quarterly email authentication check will help catch this oversight.
If you’ve spent the time to set up domain monitoring, you should take the effort to see who is trying to send unauthenticated emails from your domain. You can do this by monitoring your DMARC reports. The reports are not set up for humans to read, so you can summarize using a free tool like Postmark’s DMARC monitoring service. Postmark will send you a weekly email each Monday summarizing your DMARC reports for the week. I highly recommend it.
6. Create A Process
We’ve saved the most important step for last. Monitoring is all fine and good, but monitoring is a trailing indicator. To really create quality emails, your team must function like a well-oiled machine, and the way to achieve that is via a clear and well-thought-out email creation process.
How to create a process for and/or with a team is a topic of its own worthy not just of blog posts but entire tomes of books, but to grossly simplify it, here’s the process of creating a process:
- Map it: identify all the steps you need to take
- Discuss it: get the team in on it. Discuss and update as needed.
- Document it: write it all down in a format that will be easy and pragmatic to refer to.
Set up an approval workflow to double-check content, tech setup, and audience selection. You don’t want to make this step a bottleneck. The approval doesn’t necessarily always have to be done by the same person, but it’s important that at least two sets of eyes have reviewed each email. An editor can always see things an author cannot.
Whenever you can, test before you send. Test emails across major inboxes (Gmail, Outlook, Yahoo) and devices (desktop, mobile). Run a GlockApps spam test before big sends.
Ramp up sending volume gradually. Jumping from 1,000 emails a week to 10,000 overnight looks suspicious.
When you’re documenting, checklists are an awesome tool that can really help people implement even a complicated process. I mean, doctors and pilots use checklists, and sending emails has got to be easier than taking out an appendix or taking off in a 747.
Below is a sample email checklist. Feel free to take and adapt to fit your needs:
- Content & Design
- Copy reviewed for grammar, clarity, and tone.
- Subject line is clear, natural, and non-clickbait.
- Images optimized for fast load and correct display.
- Layout tested for mobile responsiveness.
- Brand guidelines followed (logo, colors, fonts).
- Technical Setup
- All links are tested and working.
- Personalization fields (e.g., first name) verified.
- UTM/tracking parameters applied correctly.
- Correct sender name and email address.
- Audience
- Right segment(s) selected.
- Suppression lists applied.
- List cleaned of invalid/unknown emails.
- Testing
- Rendering checked on Gmail, Outlook, Yahoo, Apple Mail.
- Mobile + desktop previews reviewed.
- Spam test run (e.g., GlockApps).
- Approvals
- Content approved by marketing lead.
- Technical setup approved by email ops/IT.
- Final sign-off by campaign owner.
- Sending Practices
- Sending volume ramped gradually (if increasing).
- Send time scheduled based on engagement data.
- Final Safety Check
- Email reviewed end-to-end by 2+ people.
- Backup copy saved of content, segment, and settings.
Final Thoughts
Email deliverability isn’t about luck or clever subject lines. Deliverability is the sum of your habits. Make sure you have good habits. Monitor your reputation, authenticate your domain, craft authentic content, engage your readers, keep your lists fresh, and stick to a well-documented process.
