Why Your Emails Are Going To Spam And How To Fix Deliverability

There are few things more frustrating in digital marketing than crafting a well-thought-out email campaign, hitting send, and then watching your open rates flatline. If your emails are consistently going to spam, or simply not being delivered at all, the problem is rarely the content itself. More often than not, it comes down to the technical foundations underpinning your sending reputation, and the good news is that most of these issues are entirely fixable once you understand what is happening behind the scenes. Email deliverability is one of those areas that gets overlooked far too often, but getting it right is absolutely fundamental to the success of any email marketing strategy.

Understanding Why Emails End Up In Spam

Before you can fix the problem, you need to understand how inbox providers like Gmail, Outlook, and others decide where your email lands. These platforms use sophisticated filtering algorithms that assess everything from your sending domain's reputation through to the specific words in your subject line. They are, in effect, acting as gatekeepers on behalf of their users, and they take that responsibility seriously. When your emails go to spam, it is because one or more signals are telling these filters that your message is potentially unwanted, untrustworthy, or poorly managed.

The reasons your emails are going to spam and how to fix deliverability issues are almost always rooted in a combination of technical shortcomings and list management problems. Addressing both is essential if you want to see meaningful, lasting improvements.

Your Authentication Records Are Missing Or Broken

Email authentication is the bedrock of deliverability, and yet it is something that a significant number of senders either overlook entirely or set up incorrectly. There are three core authentication protocols you need to have in place: SPF, DKIM, and DMARC. Together, these records tell receiving mail servers that you are a legitimate sender and that your emails are genuinely coming from the domain you claim to be sending from.

SPF, or Sender Policy Framework, is a DNS record that specifies which mail servers are authorised to send email on behalf of your domain. DKIM, or DomainKeys Identified Mail, adds a cryptographic signature to your emails that verifies the message has not been tampered with in transit. DMARC builds on both of these by telling inbox providers what to do if an email fails either check, and it also gives you visibility into how your domain is being used across the internet.

If you are sending through a platform like Mailchimp, Klaviyo, or ActiveCampaign, you will need to configure these records within your domain's DNS settings, usually through your domain registrar or hosting provider. You can check whether your authentication records are correctly configured using tools like MXToolbox, which provides a straightforward and free way to diagnose these issues.

What to do: Log in to your DNS management panel and verify that your SPF, DKIM, and DMARC records are correctly published. Your email service provider will typically provide the exact records you need to add. Do not assume this has been done automatically, as it often needs manual configuration on the domain side.

Your Sending Reputation Is Damaged

Every domain and IP address used to send email builds up a reputation over time based on how recipients interact with those messages. High spam complaint rates, low engagement, and sending to invalid addresses are all factors that will gradually erode that reputation. Once your sending reputation is damaged, even well-crafted, relevant emails can struggle to reach the inbox.

Inbox providers pay close attention to engagement signals. If a large proportion of your subscribers are not opening your emails, not clicking, or worse, marking them as spam, the algorithms begin to treat your messages with increasing suspicion. This is why buying email lists or allowing your database to go stale without regular cleaning is so damaging to long-term deliverability.

What to do: Use a tool like ZeroBounce or NeverBounce to verify and clean your email list. Remove hard bounces immediately, suppress long-term unengaged subscribers, and focus your sending on contacts who have actively opted in and shown genuine interest in hearing from you.

Your Email Content Is Triggering Spam Filters

Spam filters do not just look at technical signals. They also analyse the content of your emails, and there are certain patterns that will raise red flags almost immediately. Excessive use of capitals in subject lines, an overreliance on sales-heavy language, too many images relative to text, broken HTML, and hidden text are all characteristics commonly associated with spam.

It is worth noting that even legitimate, well-intentioned emails can trigger filters if they are not structured thoughtfully. A subject line that reads as overly promotional, or an email that is essentially one large image with very little readable text, will draw scrutiny regardless of how reputable the sender is.

What to do: Before sending, run your emails through a content checking tool such as Mail-Tester, which scores your email and highlights specific issues that could affect deliverability. Aim for a healthy balance of text and images, keep your HTML clean, and write subject lines that are relevant and clear rather than sensationalist.

You Are Sending Too Much Too Soon

If you are setting up a new sending domain or have not sent email in a while, jumping straight into large volume campaigns is one of the fastest ways to damage your deliverability before you have even had a chance to build a reputation. Inbox providers are naturally cautious about domains that suddenly begin sending high volumes of email with no prior track record.

The process of gradually increasing your sending volume over a period of weeks is known as domain warming, and it is a step that should never be skipped when starting out with a new domain or ESP. Sending to your most engaged subscribers first, in smaller batches, and then slowly scaling up gives the algorithms time to see positive engagement signals and build trust in your domain.

What to do: Follow a structured warmup plan if you are starting fresh. Begin with a few hundred emails per day sent to your most engaged contacts, and increase the volume incrementally over several weeks. Most reputable email platforms offer guidance on warmup schedules, and some even automate the process for you.

Your Unsubscribe Process Is Causing Problems

This is one of the more overlooked aspects of email deliverability, but it matters more than many senders realise. If your unsubscribe link is hard to find, broken, or requires recipients to jump through unnecessary hoops, frustrated subscribers will reach for the spam button instead. Every spam complaint carries far more weight with inbox providers than a straightforward unsubscribe, and accumulating them will damage your reputation considerably over time.

Since February 2024, Google has enforced one-click unsubscribe requirements for bulk senders, making this not just a best practice but a compliance requirement for anyone sending to Gmail addresses at scale.

What to do: Make your unsubscribe link prominent, functional, and genuinely easy to use. Honour unsubscribe requests promptly, and consider offering a preference centre where subscribers can reduce frequency rather than opting out entirely.

Fixing Deliverability Is An Ongoing Commitment

Understanding why your emails are going to spam and how to fix deliverability is not a one-time exercise. It requires consistent attention, regular list hygiene, and a genuine commitment to sending relevant content to people who actually want to receive it. The senders who achieve strong, sustained inbox placement are those who treat deliverability as an ongoing discipline rather than a technical box to tick at setup. Get the foundations right, keep your list clean, respect your subscribers, and your emails will be far better placed to land where they belong.