Gmail is blocking my emails
Gmail actively filters and rejects email that looks suspicious, comes from unauthenticated senders, or originates from domains with poor reputation. Most blocking problems are caused by missing authentication records, blacklist listings, or low sender reputation — all of which are fixable once you know where to look.
Why Gmail blocks emails
Gmail blocks emails to protect its users from spam, phishing, and malware. Blocking happens at multiple layers:
Authentication checks. Gmail verifies that incoming mail passes SPF, DKIM, and DMARC. Failing these checks signals that the message may not be from who it claims to be.
Reputation systems. Gmail maintains reputation scores for sending domains and IP addresses. Low scores cause messages to be blocked or routed to spam.
User signals. High spam complaint rates, messages moved to junk, or low engagement rates tell Gmail that recipients do not want your mail.
Suspicious sending patterns. Sudden volume spikes, sending to invalid addresses, or sending from a brand-new domain without a warmup period can trigger Gmail's defences.
Content filtering. Gmail also analyses message content for spam patterns, misleading links, and suspicious attachments.
SPF, DKIM, and DMARC problems
Missing or broken email authentication records are the most common cause of Gmail blocking.
Missing SPF. Without a valid SPF record, Gmail cannot confirm that your sending server is authorised. Gmail expects a v=spf1 TXT record listing all permitted senders.
Invalid DKIM. If your DKIM selector is missing from DNS, the key is revoked, or the signature does not match, Gmail treats the message as unsigned.
DMARC alignment failures. DMARC requires that either SPF or DKIM passes with alignment to the visible From: domain. Misaligned senders — such as third-party tools that send using your From: address — commonly cause DMARC failures.
Since February 2024, Google requires SPF and DKIM for all senders and a DMARC record for bulk senders sending more than 5,000 messages per day to Gmail. Failing these requirements increases the risk of blocking.
Blacklist and IP reputation issues
Gmail checks sending IP addresses against external DNS blacklists (DNSBLs) and maintains its own internal reputation data.
Major DNSBLs that affect Gmail deliverability include Spamhaus ZEN, Spamcop, and Barracuda. A listing on any of these can cause Gmail to block or spam-filter your messages.
Shared hosting IP problems. When you send from a shared IP address used by multiple senders, another sender's spam activity can get the IP blacklisted and affect all senders on that IP.
Compromised mailboxes. A hacked account sending spam from your domain can damage your IP and domain reputation quickly.
Spam spikes. A sudden increase in sending volume — for example after importing a large contact list — can trigger blacklisting even before any complaints are filed.
Low sender reputation
Gmail assigns reputation scores to sending domains and IPs based on historical sending behaviour. Low reputation causes messages to be blocked or routed to spam.
New domains and cold outreach. A domain with no sending history has no established reputation. Gmail applies stricter filtering until the domain earns trust through consistent, low-complaint sending.
Poor engagement. If recipients rarely open your emails, delete them without reading, or mark them as spam, Gmail interprets this as a signal that the mail is unwanted.
High bounce rates. Sending to invalid or non-existent addresses generates hard bounces that damage sender reputation.
Spam complaints. Each spam report lowers your complaint rate score in Google Postmaster Tools. Gmail recommends keeping the rate below 0.1% and enforces consequences above 0.3%.
Domain warmup. New domains and IPs should increase sending volume gradually over several weeks, starting with your most engaged contacts.
SMTP TLS and server security
Gmail expects mail servers to support encrypted connections using STARTTLS. While TLS failures alone rarely cause Gmail to block messages outright, they affect trust signals and can contribute to blocking alongside other issues.
STARTTLS. Your outbound mail server must advertise and support STARTTLS. Gmail prefers encrypted transport and may flag unencrypted connections.
Expired or invalid TLS certificate. A certificate that is expired, self-signed, or does not match the server hostname reduces trust.
Weak TLS configuration. Old TLS versions (TLS 1.0, TLS 1.1) or weak cipher suites can be flagged by security scanning tools.
MTA-STS. Publishing an MTA-STS policy requires sending servers to use TLS when delivering mail to your domain and signals a stronger commitment to transport security.
How to stop Gmail from blocking your emails
Follow this checklist to diagnose and resolve Gmail blocking:
Run SPF Checker. Verify your SPF record exists, is valid, and does not have multiple records or exceed the 10 DNS lookup limit.
Run DKIM Checker. Confirm your DKIM selector is present in DNS and the key is not revoked or in test mode.
Run DMARC Checker. Verify a DMARC record is published and that SPF and DKIM pass with alignment to your From: domain.
Run Blacklist Checker. Check whether your sending IP or domain is listed on Spamhaus ZEN, Barracuda, Spamcop, or other DNSBLs.
Run SMTP TLS Checker. Verify that your mail server supports STARTTLS and uses a valid, non-expired TLS certificate.
Run Email Security Score. MXFend's comprehensive scan covers SPF, DKIM, DMARC, MX, blacklists, SMTP TLS, BIMI, MTA-STS, and TLS-RPT in a single weighted report.
Use Google Postmaster Tools. Monitor your domain reputation, IP reputation, spam rate, and DMARC compliance directly in Gmail's Postmaster Tools dashboard.
Warmup gradually. If your domain or IP is new, gradually increase sending volume over several weeks, starting with your most engaged recipients.
Frequently asked questions
Why is Gmail blocking my emails?
Gmail blocks emails because of missing authentication (SPF, DKIM, DMARC), poor sender reputation, blacklist listings, suspicious sending patterns, or content that resembles spam. Fixing authentication records is usually the fastest first step.
Can Gmail block emails with valid SPF?
Yes. SPF is one signal among many. Even with valid SPF, Gmail can block or spam-filter messages because of poor sender reputation, blacklist listings, missing DKIM, DMARC failures, or content issues.
How do I improve Gmail sender reputation?
Warm up new domains gradually, send only to engaged recipients, keep spam complaint rates below 0.1%, reduce bounce rates by validating address lists, and configure SPF, DKIM, and DMARC correctly.
How do I check if Gmail trusts my domain?
Run MXFend's Email Security Score to audit authentication, blacklists, and transport security. Then check Google Postmaster Tools for Gmail-specific domain reputation, IP reputation, and spam rate data.