Why are my emails going to spam?
Spam placement is usually caused by a combination of technical authentication failures, poor sender reputation, blacklist listings, and content issues. Most email deliverability problems are fixable once you identify the root cause.
Why emails go to spam
Email providers like Gmail, Outlook, and Yahoo use layered filtering systems to decide whether a message belongs in the inbox or spam folder.
These filters evaluate authentication records (SPF, DKIM, DMARC), sending IP and domain reputation, DNS health, content quality, engagement history, and transport security.
No single factor sends email to spam — it is usually a combination of weak authentication, questionable reputation, and content signals that together push a message below the inbox threshold.
SPF, DKIM, and DMARC authentication failures
Missing or misconfigured authentication records are the most common cause of spam placement.
SPF (Sender Policy Framework) tells receiving servers which IP addresses are allowed to send email for your domain. A missing SPF record means receivers cannot verify your sending server.
DKIM (DomainKeys Identified Mail) attaches a cryptographic signature to each outgoing message. Without a valid DKIM signature, receivers cannot confirm the message has not been tampered with in transit.
DMARC ties SPF and DKIM together and tells receivers what to do when authentication fails. Without DMARC, or with p=none and no enforcement, spoofed and unauthenticated mail passes through without any action.
Use the MXFend SPF Checker, DKIM Checker, and DMARC Checker to identify authentication gaps on your domain.
Sender reputation and domain reputation
Sender reputation is built from the history of email sent from your domain and IP address.
High spam complaint rates, hard bounce rates, low engagement, and sending to purchased or scraped lists all damage reputation over time.
Sudden sending volume spikes on a new or low-volume domain trigger additional scrutiny. Mail providers expect consistent, gradual volume growth rather than large bursts from domains without history.
Even with correct SPF, DKIM, and DMARC, a domain or IP with poor reputation will see messages filtered to spam.
Blacklist and blocklist problems
DNS blacklists (DNSBLs) are real-time lists of IPs and domains flagged for spam, malware, or abuse.
Major mail providers check services like Spamhaus ZEN, Barracuda, Spamcop, and others as part of their filtering pipeline. A listing on any major DNSBL can cause messages to go directly to spam or be rejected before delivery.
IPs can become blacklisted because of spam complaints, compromised accounts sending bulk mail, poor list hygiene, or hosting abuse.
Use the MXFend Blacklist Checker to test whether your sending IP or domain is listed on major DNSBLs.
Content and engagement signals
Spam filters analyse message content as part of the filtering decision.
Trigger factors include: misleading or deceptive subject lines, excessive URLs, broken HTML, invisible or hidden text, spam-associated keywords, suspicious attachments, and mismatched From headers.
Engagement signals also matter. If recipients consistently ignore, delete, or mark your messages as spam, providers learn that your mail is unwanted and apply stronger filtering.
Maintaining a clean sending list, removing inactive subscribers, and sending relevant content all improve engagement and inbox placement.
DNS, PTR, HELO, and SMTP TLS issues
Several DNS and transport-layer problems can contribute to spam placement even when SPF, DKIM, and DMARC are correctly configured.
Missing PTR record. A sending IP without a reverse DNS (PTR) record is considered suspicious by many filters. The PTR should resolve to a hostname that forward-confirms back to the IP.
HELO mismatch. The hostname used in the SMTP HELO/EHLO greeting should match the PTR record of the sending IP. Mismatches raise spam scores.
SMTP TLS problems. Modern mail providers expect encrypted transport using STARTTLS. Expired TLS certificates, unsupported cipher suites, or missing STARTTLS support reduce trust and can affect deliverability.
Use the MXFend SMTP TLS Checker to verify TLS configuration and certificate validity for your mail server.
How to fix emails going to spam
Work through authentication first: publish a valid SPF record, configure DKIM signing for all outgoing mail, and set a DMARC policy of at least p=quarantine once SPF and DKIM are passing consistently.
Check blacklists: if your sending IP is listed on a major DNSBL, submit a delisting request after identifying and fixing the underlying cause.
Review DNS: ensure your sending IP has a PTR record, verify HELO/EHLO hostname alignment, and confirm your TLS certificate is valid.
Improve list hygiene: remove hard bounces immediately, suppress inactive subscribers, and never send to purchased lists.
Warm up sending volumes gradually if you are on a new IP or domain, starting with low volumes and increasing over weeks.
Audit content: avoid spam-trigger keywords, fix broken HTML, and use clear, accurate subject lines.
How MXFend can help diagnose the problem
MXFend provides dedicated checkers for each layer of email deliverability:
SPF Checker — validates your SPF record syntax, lookup count, and authorised senders.
DKIM Checker — verifies DKIM selector records, key length, and signature validity.
DMARC Checker — checks your DMARC policy, alignment mode, and reporting configuration.
Blacklist Checker — tests your sending IP against major DNSBLs.
SMTP TLS Checker — checks STARTTLS support and TLS certificate health.
Email Security Score — runs a comprehensive audit across all of the above in a single weighted report, giving you a prioritised list of issues to fix.
Frequently asked questions
Why are my emails going to spam?
Emails go to spam because of missing or broken SPF, DKIM, or DMARC records, poor sender reputation, blacklist listings, suspicious content, DNS misconfiguration, or SMTP TLS problems. Usually it is a combination of several factors rather than a single cause.
Can SPF, DKIM, and DMARC stop emails going to spam?
Authentication records are the foundation of inbox placement. Correct SPF, DKIM, and DMARC reduce spam placement significantly, but they do not guarantee inbox delivery on their own. Reputation, content quality, and engagement also matter.
Can emails go to spam even if DMARC passes?
Yes. DMARC passing means authentication is correct, but spam filters also evaluate sender reputation, blacklist status, content quality, and engagement history. A domain with poor reputation can still land in spam despite passing all authentication checks.
How do I check if my domain is causing spam placement?
Run a MXFend Email Security Score scan to audit SPF, DKIM, DMARC, blacklist status, SMTP TLS, and DNS configuration. Use the individual checkers to investigate specific layers in detail.
How can I fix emails going to spam?
Fix authentication first by publishing valid SPF, DKIM, and DMARC records. Check for blacklist listings and delist if needed. Review DNS health including PTR records and SMTP TLS. Improve list hygiene, warm up sending volumes gradually on new domains, and audit email content for spam signals.