A 550 Administrative Prohibition is a firm rejection from the receiving mail server, indicating that your message has been blocked because it violates a recipient policy. Unlike a temporary 4xx deferral, this is a “hard bounce” and resending messages without resolving the underlying issue will not succeed.
550 5.7.1 Administrative prohibition. Message not accepted due to policy.
550 Administrative prohibition – envelope blocked for this recipient.
You’ll often see sub‑codes such as 550 5.7.1 or 550 5.7.0, which indicate a policy or security violation. By comparison, 550 5.1.1 means the mailbox doesn’t exist. Reading the full error code and message is your first step toward finding the right solution.
Work methodically from the bounce message to the source of the problem. Follow a systematic approach in diagnosing the issue, and avoid jumping to conclusions without thoroughly investigating each possible cause.
dig TXT example.comdig TXT default._domainkey.example.comdig TXT _dmarc.example.comhost 203.0.113.25nslookup -type=txt example.comopenssl s_client -starttls smtp -crlf -connect mx.example.net:25If the server’s response refers to a postmaster or support page, review it closely. Many providers include detailed instructions or forms for appeal.
-all once stable.d= domain matches your visible From address.p=none to monitor pass rates. Progress to quarantine or reject after confirming consistent success.v=spf1 include:mail.example.net -allv=DMARC1; p=none; rua=mailto:dmarc-reports@example.com; fo=1mode: enforce after monitoring; this reduces TLS downgrade risks and strengthens transport security posture in 2024–2025.Email service providers have tightened their acceptance rules in recent years to improve security and ensure the relevance of incoming mail. If you need to understand how new standards affect delivery, read this detailed guide on email bounces and new delivery policies for 2025.
After being blocked by a 550 policy error, increasing volume quickly is rarely effective. Instead, you should focus on generating positive interaction signals and establishing consistent mail flow with a controlled approach called warm-up.
Mail warm-up builds sender reputation by simulating real engagement, messages are opened, replied to, and retrieved from spam by active mailboxes in a managed network. This consistent, genuine-looking traffic demonstrates to mailbox providers that your domain behaves like a trusted sender. The key is to maintain steady, low-risk activity before resuming normal sending.
Mailwarm offers an automated warm-up solution, running structured mailbox interactions to gradually restore trust, tag emails to the inbox, and ensure normalized delivery behavior. This is strictly technical activity, separate from marketing campaigns.
When your sending metrics improve, phase production emails back in while continuing warm-up. If you still see 550 errors from a particular provider, slow the ramp and keep focusing your warm-up on the affected domains.
Sometimes, blocks are unique to a specific recipient organization. Their administrators may enforce custom policies not covered by general fixes. If your review confirms that your logs and sender configuration are clean, reach out to their postmaster or support team and provide detailed, professional evidence for review or allowlisting.Keep your correspondence professional and fact-based. Include specific information such as timestamps, message IDs, and the results of any tests or checks that have been completed. Providing concrete evidence and a summary of actions taken will usually yield a faster, more favorable response from administrators.
To diagnose these edge cases, test each scenario step by step, send a plain text message first, and only add complexity incrementally.
A 550 Administrative Prohibition is a clear signal that your email needs specific policy, authentication, or reputation fixes, it will not resolve on its own or with repeated sending. Carefully review error details, confirm server identity and authentication records, and address any issues with sender reputation. Proceed slowly as you restore your sending profile, and maintain steady, authentic activity to rebuild trust with recipient systems.
Want personalized help with a persistent 550 error? Consult with email deliverability experts at MailAdept for in-depth analysis, log reviews, and a safe, customized warm-up and remediation plan for your stack.
This error tells you that your email has been blocked due to a policy violation on the recipients server. Its a hard bounce, meaning resending without resolving the problem is futile.
Neglecting DNS authentication, like SPF and DKIM, is a cardinal sin in email delivery. It instantly flags your emails as untrustworthy, risking them getting caught in policy traps.
Resending without addressing the underlying issue is pointless and potentially damaging. It signals to recipient servers that youre careless about compliance, worsening your reputation.
No quick fixes exist; reputation recovery is a marathon, not a sprint. Implementing email warm-up strategies and gradually rebuilding trust is more effective than brute force resending.
Ignoring attachment rules shows youre courting disaster. Compliance with file type restrictions is non-negotiable; circumventing these rules risks your emails being flagged and blocked.
Inconsistent sending rates can scream spammy behavior to email providers. Abrupt volume spikes damage your reputation and invite tighter scrutiny on future deliveries.
Reaching out can be strategic early on, but only after thorough self-assessment and resolution attempts. It demonstrates you value their input and are earnest about fixing issues.
Overlooking geographic policies is reckless. Blocks against specific IP ranges arent random; breaching them can permanently banish your emails from these servers.
Yes, edge scenarios like misrouted emails or failing to rewrite envelope senders can result in 550 errors. Ignoring these nuances implies a complacent approach that could trap you in a cycle of failures.