How to stop spam emails: what works for senders and recipients in 2026

Why spam is still a problem for senders and recipients

Spam is a problem from two directions. Recipients deal with unwanted messages clogging their inboxes. Senders deal with legitimate emails being filtered into spam folders where no one reads them. The two problems have overlapping causes, and many of the same practices that protect recipients from spam also protect senders from being treated as spammers.

For senders, the core spam problem is inbox placement. An email that goes to the spam folder does not get opened, does not get clicked, and does not drive any result. It may as well not have been sent. The cost of poor deliverability is invisible in your sending platform if you are only watching delivery rate, because delivered emails include everything that reached the recipient's server, whether it landed in the inbox or not.

For recipients, the spam problem is volume and persistence. Unsubscribing from legitimate mailing lists is straightforward, but spam from unknown senders is harder to stop because the senders are not following the rules that make unsubscription work. Understanding how spam filtering actually functions helps recipients use their email client settings more effectively, and it helps senders understand exactly what mailbox providers are trying to filter out.

The full picture of how email deliverability works, including how sender reputation is scored and how authentication protects your domain, is covered in the email deliverability guide. This article focuses specifically on the practical actions that reduce spam, both for senders protecting their sending reputation and for anyone trying to reduce the volume of unwanted email they receive.

How to stop your own emails being marked as spam

The most common cause of legitimate emails landing in spam is poor sender reputation. Reputation is scored at the domain level, and it reflects how recipients have responded to your emails over time. High complaint rates, low open rates, and sending to invalid addresses all degrade reputation. Improving it requires addressing each of those signals directly.

Start by checking your current situation. Google Postmaster Tools gives you free, domain-level data on how Gmail recipients classify your emails, including complaint rate, IP reputation, domain reputation, and authentication pass rates. If you are sending to significant numbers of Gmail recipients and are not using Postmaster Tools, set it up now. It is the most direct window into how the world's largest mailbox provider sees your sending programme.

Next, check whether your emails are reaching the inbox at all. Tools like Mailchimp and HubSpot report delivery rates and engagement metrics, but inbox placement requires dedicated seed-list testing. Running a test before a major campaign tells you where your email actually lands across Gmail, Outlook, Yahoo, and Apple Mail before you send to your real audience.

If your complaint rate is above 0.1%, the most urgent action is to identify which segments of your list are generating complaints. Recent subscribers who engaged recently are rarely the source. Long-inactive subscribers, people who never opened their first email, or contacts imported from old or purchased lists are much more likely to mark your emails as spam. Removing or suppressing those contacts reduces your complaint rate faster than any content change.

Senders using HubSpot can use engagement-based segmentation to separate active contacts from inactive ones before each send, making it straightforward to restrict campaigns to engaged segments during a deliverability recovery period. The email deliverability guide covers the full re-engagement and list cleaning process in detail.

List management habits that protect your sender reputation

List management is not a one-time task. It is an ongoing practice that directly determines the engagement signals mailbox providers use to score your domain reputation. The habits below, applied consistently, prevent most spam filtering problems before they start.

Use double opt-in for all new subscribers. Double opt-in requires new contacts to confirm their email address before they join your list. This eliminates typos, fake addresses, and people who did not genuinely request your emails. Lists built on double opt-in consistently show higher open rates and lower complaint rates than single opt-in lists because every subscriber actively chose to be there.

Set expectations at sign-up. Tell subscribers what they will receive and how often. People who receive email they did not expect are far more likely to mark it as spam than to unsubscribe. A simple confirmation email that sets expectations reduces complaint rates and sets a better foundation for the relationship.

Remove hard bounces immediately. A hard bounce means the address does not exist. Continuing to send to it tells mailbox providers you are not maintaining your list. Most platforms suppress hard bounces automatically, but check your suppression settings when you first set up an account or import contacts from another source.

Run re-engagement campaigns before removing inactive subscribers. Rather than deleting inactive contacts silently, send a short re-engagement sequence first. Two or three emails with a clear message gives genuinely interested subscribers a chance to confirm they still want to hear from you. Those who do not respond can be suppressed without the engagement data loss of an immediate removal.

Never buy or scrape email lists. Purchased lists contain spam traps, invalid addresses, and people who never consented to hear from you. Sending to them damages your domain reputation at the ISP level and can result in blacklisting. The short-term list size gain is not worth the deliverability damage, which can take months to recover from.

Managing bounce rates is closely tied to list management quality. The email bounce rate guide covers hard and soft bounce thresholds, suppression processes, and how to reduce bounce rates on existing lists in detail.

Technical spam prevention: SPF, DKIM, and DMARC

Authentication records are the technical layer that proves your emails are genuinely from you. Without them, receiving servers have no way to verify that an email claiming to come from your domain was actually sent by you, which makes it look suspicious regardless of content quality.

Three DNS records handle email authentication. SPF (Sender Policy Framework) lists the IP addresses and mail servers authorised to send email on your behalf. DKIM (DomainKeys Identified Mail) adds a digital signature to every email, which receiving servers verify against a public key in your DNS. DMARC ties the two together and tells receiving servers what to do with emails that fail either check.

Setting up all three is mandatory for serious sending in 2026. Google and Yahoo tightened bulk sender requirements in early 2024, requiring SPF, DKIM, and DMARC for senders dispatching more than 5,000 emails per day to their users. Below that volume, missing authentication still significantly increases the risk of spam filtering. If you are sending commercial email and have not set up all three records, this is the first thing to fix.

Most major platforms, including Mailchimp and HubSpot, provide the exact DNS records you need to add during account setup. The process involves copying a TXT record for SPF and a CNAME or TXT record for DKIM into your domain registrar's DNS settings. DMARC requires you to create your own policy record, starting with p=none to monitor without blocking, then escalating to p=quarantine or p=reject as you confirm no legitimate sending sources are failing.

Once all three are published, verify them using a free tool like MXToolbox or the built-in authentication checker in your sending platform. A passing result on all three means receiving servers can confirm your identity, which removes one of the most common spam filtering triggers. Ongoing monitoring is covered in the email deliverability guide alongside the broader tools and tracking setup that keeps a sending programme healthy.

Compliance with email marketing regulations also reduces spam risk by ensuring your programme follows the consent and unsubscription standards that mailbox providers reward. Understanding your obligations under GDPR and local regulations is part of running a legitimate programme. The GDPR email marketing guide covers consent documentation, lawful basis for sending, and what to do with non-compliant legacy lists.

What to do if your domain is blacklisted

A blacklisting means an anti-spam organisation has identified your domain or sending IP as a source of spam and added it to a list that receiving servers check. Many receiving servers use multiple blacklists simultaneously, so a single blacklisting can affect inbox placement across a wide range of recipients.

The first step is to find out which blacklists you are on. Free tools like MXToolbox check your domain and IP against the major blacklists in seconds. Run a check on both your sending domain and your sending IP address, since both can be listed independently.

The second step is to identify and fix whatever caused the blacklisting before requesting removal. Blacklist operators will reject delisting requests from senders that are still sending spam. Common causes include: sending to a spam trap address, a sudden spike in complaint rates, sending to a large number of invalid addresses, or a compromised account that was used to send spam without your knowledge. Check your sending platform's complaint and bounce reports for the period around when the blacklisting occurred.

Once the root cause is fixed, visit the blacklist operator's website and submit a delisting request. Major operators including Spamhaus and Barracuda have public delisting processes. Most remove legitimate requests within 24 to 72 hours. Some blacklists expire automatically after a period of clean sending without requiring a request.

During a blacklisting event, reduce your send volume significantly and focus on your most engaged segment only. High engagement signals from your active subscribers help rebuild reputation while the blacklisting is being resolved. Sending full-volume campaigns during a blacklisting compounds the problem.

Following the list management habits and authentication setup described above makes blacklisting very unlikely for senders who start from scratch with permission-based contacts. For senders with legacy lists or unclear consent history, the email marketing best practices guide covers how to audit and clean existing programmes before they develop deliverability problems.

What this means for your email reach

Spam filtering determines whether anyone reads your email. A technically correct, well-written email to a disengaged list will land in spam. A straightforward, plainly formatted email to a highly engaged, permission-based list will land in the inbox consistently. The content matters less than the context in which it arrives.

The practical actions that reduce spam are also the practices that build a sustainable sending programme. Sending only to people who asked to hear from you, making it easy for them to stop receiving email, maintaining your authentication records, and monitoring your engagement metrics are not just deliverability tactics. They are the foundation of a programme that recipients trust and that mailbox providers treat as legitimate.

If you are working through a deliverability problem right now, start with the quick diagnostic: check Google Postmaster Tools for your complaint rate, verify SPF, DKIM, and DMARC with MXToolbox, check for blacklistings, and identify your least engaged segments. Fix authentication first if anything is failing. Then address list quality. Content is the last thing to adjust, and usually the one that needs it least.