Why are T-online.de and Arcor.de hard bouncing with local policy and permission errors?
Matthew Whittaker
Co-founder & CTO, Suped
Published 20 Jul 2025
Updated 16 Aug 2025
8 min read
Suddenly seeing a surge in hard bounces from T-online.de and Arcor.de can be a frustrating experience, especially when your email practices haven't seemingly changed. I've heard from many senders who encounter this, reporting errors like "5.7.0 Local Policy Violation," "5.7.1 Permissions problem," and general "Unspecified error during delivery." These specific bounce codes indicate that the receiving mail servers at Deutsche Telekom (for T-online.de) and Vodafone Germany (for Arcor.de) are actively rejecting your emails due to their internal policies.
The challenge intensifies because these are hard bounces, meaning the emails are permanently undeliverable to those addresses. Unlike soft bounces, which are often temporary, hard bounces signal a fundamental issue that requires immediate attention.
Many senders, myself included, have found that traditional troubleshooting methods, like basic email analysis or testing tools, often don't immediately reveal the specific trigger for these blocks. This article will explain why these German providers are so particular and outline the steps you can take to diagnose and fix these persistent bounce issues.
Understanding T-online.de and Arcor.de bounce codes
When you receive a bounce message, the error codes offer crucial clues about the underlying problem. For T-online.de and Arcor.de, the messages "5.7.0 Local Policy Violation" and "5.7.1 Permissions problem" are particularly common.
The "5.7.0 Local Policy Violation" error typically means that your email was rejected because it violates a specific rule or policy set by the recipient's mail server. This isn't necessarily a universal spam block, but rather a targeted rejection based on something the ISP deems unacceptable, which could be related to your sender reputation, authentication, or even the content of your email. In many cases, it points to your IP or domain being added to an internal (private) blocklist (or blacklist) at their end, preventing mail from reaching the inbox.
The "5.7.1 Permissions problem" message suggests that the sender is not authorized to email the specific recipient account. While it might sound like an issue with sending to a mailing list that doesn't allow non-subscribers to post, it can also signify broader authentication or authorization failures where the receiving server doesn't trust your sending identity. Both T-online.de and Arcor.de (which handles domains like arcor.de, arcormail.de, and others for Vodafone Germany) are known for their particularly strict email policies, often more stringent than other major global ISPs like AOL or Yahoo.
An "Unspecified error during delivery" is less helpful, but often occurs when the initial policy or permission check fails without a more specific diagnostic code. It's usually a symptom of the same underlying issues causing the more detailed bounce messages.
Error code
Typical meaning
Relevance for T-online.de and Arcor.de
5.7.0
Local policy violation
Often indicates an internal block or blacklist due to reputation or content.
A catch-all for various failures, often linked to policy violations.
Why your emails are getting blocked
A sudden spike in hard bounces often points to a shift in how T-online.de or Arcor.de perceive your sending practices. Even if you haven't made any obvious changes, subtle shifts in volume, content, or recipient engagement can trigger their filters.
Sender reputation decline
A primary culprit is a decline in your sender reputation. This can happen if your spam complaint rates increase, if you're sending to a lot of inactive or unknown users, or if you've recently experienced a spam trap hit. German ISPs (internet service providers) are particularly sensitive to these signals. Even if your list is double opt-in, as many German companies require, the age of the subscribers or a lack of recent engagement can still impact your standing. They might have a stricter policy on what constitutes an acceptable sender based on perceived engagement and list quality.
IP and domain blocklisting
Your IP address or sending domain might have ended up on an internal blacklist (or blocklist) maintained by T-online.de or Arcor.de. This is distinct from public DNSBLs (DNS-based Blackhole Lists). We've observed instances where they proactively block entire IP ranges, especially those from specific hosting providers, even if individual IPs within those ranges haven't been directly sending spam. This can disproportionately affect smaller senders using shared IPs or IPs within these ranges.
Authentication issues
Authentication setup for T-online.de
SPF: Ensure your SPF record is correctly configured to authorize all sending IPs.
DKIM: Implement DKIM signing for all your outgoing mail to ensure message integrity.
DMARC: Set up a DMARC policy to enforce alignment and gain visibility into authentication failures.
rDNS: Reverse DNS (rDNS) for your sending IP address should correctly map to your sending domain. This is a common requirement.
T-online.de, in particular, has very specific requirements for email authentication, including DKIM alignment and reverse DNS (rDNS) configuration. If your SPF, DKIM, or DMARC records are misconfigured or if there's a lack of rDNS, these providers are highly likely to reject your emails with a local policy or permissions error. I've seen cases where even minor discrepancies can lead to significant bounce rates, impacting overall email deliverability.
Resolving hard bounces from T-online.de and Arcor.de
Addressing these hard bounces requires a systematic approach, starting with confirming your current standing with these ISPs and then taking corrective action.
Contacting the postmaster teams
The most direct route to resolving these blocks is to contact the postmaster teams at T-online.de and Arcor.de. They can often provide specific reasons for the block or give you instructions on how to get unblocked.
Contacting postmasters: common mistakes
Lack of detail: Sending a vague request without bounce messages, sending IPs, or domain information.
Impatience: Expecting an immediate resolution, as investigations can take time.
Aggressive tone: Being demanding or blaming the ISP, which can hinder resolution.
Tips for contacting postmasters
Gather information: Collect full bounce messages, sending IP addresses, the domain in question, and a brief history of your sending practices to these providers.
Be polite and professional: Understand that they handle many inquiries. A courteous approach will yield better results.
Use their official channels: For T-online.de, use their dedicated postmaster contact form. Arcor.de (Vodafone) might require a different approach, potentially through a general abuse contact.
Reviewing sender authentication and infrastructure
Even with double opt-in, it's crucial to continuously review your email authentication. Use a deliverability tester to ensure your SPF, DKIM, and DMARC records are perfectly configured and aligning correctly. Misconfigurations, such as SPF `TempError` or DKIM temperror issues, can cause these specific bounces.
Also, verify your reverse DNS (rDNS) is correctly set up for your sending IP addresses. T-online.de specifically checks for this. If you are using a new IP or a different sending platform, ensure all DNS records are propagated and verified.
Maintaining healthy email deliverability to German ISPs
Preventing future hard bounces from T-online.de and Arcor.de requires a proactive and continuous approach to your email program.
Maintain impeccable list hygiene
Even with a double opt-in process, regularly clean your email lists. Remove inactive subscribers who haven't engaged with your emails in a long time, as these can become recycled spam traps. Implement processes to automatically suppress hard bounces to prevent further damage to your reputation. A clean list signals to ISPs that you are a responsible sender.
Monitor your sender reputation
Consistently monitor your email domain reputation across various tools and platforms. Keep an eye on your complaint rates and bounce rates specifically for German domains. Early detection of a decline can help you act before widespread blocking occurs. Regular blocklist (or blacklist) monitoring is also essential, although remember that many ISP-specific blocks are internal.
Adhere to sending best practices
Ensure your content is relevant and engaging, avoiding anything that could be perceived as spammy. Maintaining consistent sending volumes and adhering to a regular sending schedule can also help build trust with ISPs. For more detailed insights, explore our guide on boosting email deliverability.
Views from the trenches
Best practices
Actively monitor your DMARC reports to identify authentication failures and sources of non-compliant email.
Regularly review your email lists for inactive subscribers and remove them to improve engagement rates.
Ensure all sending IPs have correct rDNS records that resolve back to your domain.
Segment your audience and send targeted content to improve engagement and reduce complaints.
Always use a double opt-in process, especially for German subscribers, and clearly state your privacy policy.
Common pitfalls
Ignoring local policy bounce messages, assuming they are temporary and will self-resolve.
Not maintaining clean email lists, leading to higher bounce rates and spam trap hits.
Failing to properly configure SPF, DKIM, and DMARC, leading to authentication failures at strict ISPs.
Sending emails from newly warmed-up IPs or IP ranges that may be blocked by specific ISPs like T-online.de.
Not engaging directly with ISP postmaster teams when experiencing significant blocking issues.
Expert tips
German ISPs often have very specific and strict technical requirements for authentication, so ensure SPF, DKIM, and DMARC are impeccable.
If using cloud hosting providers, be aware that some IP ranges might be preemptively blocked by German ISPs due to past abuse.
Always contact the ISP's postmaster directly with comprehensive details of your issue and sending practices.
Implement feedback loops where possible to quickly identify and suppress users who mark your emails as spam.
Consistency in sending volume and content quality is key to building and maintaining trust with German mail servers.
Expert view
Expert from Email Geeks says a "Local policy violation" error explicitly indicates that your emails are being blocked by the recipient's server due to their internal rules.
2022-10-18 - Email Geeks
Expert view
Expert from Email Geeks says a "Permissions problem" often means the sender is not authorized to send to a particular mailing list, or there's a broader issue with sender legitimacy.
2022-10-18 - Email Geeks
Securing your email path to German inboxes
Dealing with hard bounces from T-online.de and Arcor.de can be particularly challenging due to their strict local policies and specific technical requirements. The key is to recognize that these aren't random occurrences but rather signals that your sending practices, authentication, or sender reputation may not be meeting their high standards. While it can be frustrating, these bounces are actionable if you know where to look.
By proactively engaging with their postmaster teams, meticulously verifying your email authentication (SPF, DKIM, DMARC, rDNS), maintaining stringent list hygiene, and consistently monitoring your sender reputation, you can significantly improve your chances of reaching the inbox for these crucial German audiences. Remember, successful email deliverability is an ongoing process of adaptation and optimization.
