How to troubleshoot B2B email quarantine issues with new dedicated IPs and strict security settings?

Key findings

• New IP sensitivity: Strict B2B security filters (like Proofpoint or Mimecast) are highly sensitive to new IP addresses, even when associated with a long-established and trusted domain.
• DMARC authentication: Proper DMARC (Domain-based Message Authentication, Reporting, and Conformance) configuration, especially for subdomains used for sending, is crucial to prevent emails from being flagged. A p=none DMARC policy on a subdomain might not provide sufficient protection against quarantine by strict filters.
• IP warming importance: Despite having a good domain reputation, new dedicated IPs require a careful IP warming process to build trust with recipient servers and avoid deliverability issues, including quarantine.
• Recipient-side configuration: Often, the issue lies with the recipient's internal email security settings, which might require their IT administrators to whitelist the new sending IP addresses or domain.
• Testing nuance: Testing emails by sending to one's own internal domain may not accurately reflect external deliverability, as internal systems often have different rules or whitelisting configurations.

Key considerations

• Comprehensive authentication: Ensure that SPF, DKIM, and DMARC are correctly configured for both the main domain and any subdomains used for sending. A robust DMARC policy (e.g., p=quarantine or p=reject) that aligns with your sending practices can significantly improve trust with recipient servers.
• Proactive communication: Inform your customer base about the change in sending platform and new IP addresses. Encourage them to add your new sending IP or domain to their whitelist or trusted sender list.
• Gradual IP warming: Implement a structured IP warming plan. This involves gradually increasing email volume over time to build a positive reputation for the new IPs. For B2B, this often means segmenting your audience and starting with your most engaged recipients.
• Engage recipient IT: When issues arise, advise your customers to contact their IT department or email filter provider (like Proofpoint) to investigate the quarantine. They can often provide specific reasons for blocking or adjust their settings.
• External testing: Rely on external testing to various mailbox providers (Gmail, Outlook, Yahoo) to gauge actual inbox placement. This provides a more accurate picture than solely testing within your own network.

Key opinions

• Platform change impact: Changing ESPs or introducing new dedicated IPs, even with the same domain, can trigger heightened scrutiny from B2B security systems.
• Internal domain complexity: Testing deliverability to one's own corporate domain is unreliable because internal filters often have unique rules or pre-existing whitelists that don't apply to external recipients. It adds a level of complexity that can mask true deliverability issues.
• Whitelisting as a solution: A common suggestion is to ask the customer base to whitelist the new email address or IP range, especially when dealing with strict corporate firewalls.
• Company-specific rules: Many companies implement strict spam rules where IPs dedicated for internal communication might need explicit whitelisting to avoid quarantines, even for legitimate B2B correspondence.

Key considerations

• Proactive communication: It is advisable to inform recipients in advance about the sending platform change and new IP addresses. This can help set expectations and potentially prompt IT departments to make necessary adjustments.
• External testing: Prioritize testing to external domains (e.g., Gmail, Outlook, other business domains not associated with the sender) to get an accurate view of deliverability. If these tests pass, the issue is likely on the customer's end.
• Support engagement: Be prepared to guide customers on reaching out to their email filter providers (like Proofpoint) for specific insights into why emails are being quarantined. Sometimes, a direct query to the filter provider is the most effective way to resolve specific blocking issues related to new IPs or domains.
• Review authentication: Double-check SPF, DKIM, and DMARC configurations for the new setup. Even a minor misconfiguration can cause significant deliverability hurdles, leading to emails landing in spam or quarantine.

Key opinions

• Authentication rigor: Experts consistently point to email authentication (SPF, DKIM, and DMARC) as the first line of defense. A DMARC policy of p=none, especially on a subdomain, may not be sufficient for strict B2B filters.
• Proofpoint behavior: Proofpoint, a common B2B email security provider, is generally not known to have significant warmup issues. If emails are quarantined, it's more likely due to specific configuration or policy enforcement rather than just new IP reputation. Direct engagement with their support is often recommended.
• Internal vs. external distinction: Sending to your own domain for testing can give a false sense of security. Corporate networks often treat internal emails or emails from known internal domains differently than external mail, even if authenticated. This adds a layer of complexity.
• Recipient IT role: When deliverability issues persist, the solution frequently lies with the recipient's IT team or mail administrator, who may need to adjust their internal filtering rules or whitelist the sending IP or domain.

Key considerations

• Verify DMARC alignment: Ensure that your DMARC records are not only present but also configured for strict alignment (aspf=s, adkim=s) and a policy stronger than p=none, such as p=quarantine, as appropriate for your sending volume and reputation.
• Engage filter providers: If Proofpoint or similar B2B filters are the barrier, encourage the customer to contact their support team. They can provide detailed logs and explanations for why emails are being quarantined.
• Monitor deliverability: Continuously monitor deliverability to various B2B domains and major mailbox providers (e.g., Gmail, Microsoft 365) to quickly identify and address new issues during the IP warming period and beyond.
• Educate customers: Provide clear guidance to customers on how to communicate with their IT departments regarding whitelisting or reviewing their email security appliance configurations.

Key findings

• Dedicated IP benefits: Documentation from major email service providers highlights that dedicated IPs give senders more control over their sender reputation, minimizing the risk of issues caused by other users on shared IP addresses.
• Authentication enforcement: With evolving standards, mailbox providers (like Microsoft and Google) are increasingly enforcing strict authentication policies (SPF, DKIM, DMARC). Failure to comply can lead to email quarantines or rejections.
• Sender reputation building: New IPs, even when associated with a known domain, start with a neutral reputation. Documentation emphasizes the necessity of a structured IP warming process to build a positive sending history and establish trust with recipient servers.
• Quarantine mechanisms: Email security solutions for businesses often utilize advanced filtering that quarantines emails based on multiple factors, including sender reputation, authentication status, and content, even if the domain is familiar.

Key considerations

• Aligning DMARC: Official documentation from email providers often specifies requirements for DMARC alignment, which ensures that the domain in the From header aligns with the SPF or DKIM authenticated domain. Misalignment can lead to deliverability issues even with a p=none policy.
• Monitoring deliverability: Leverage tools like Google Postmaster Tools (for Gmail recipients) or similar dashboards provided by email security vendors to monitor email performance, sender reputation, and DMARC reports. This helps in diagnosing specific issues.
• B2B security configurations: Understanding that B2B recipients often have enhanced security solutions (e.g., Microsoft Defender for Office 365, Proofpoint) is key. These systems may require specific configurations, such as adding sending IPs to a safe sender list, to bypass quarantine.
• Email content & list hygiene: Beyond technical setup, documentation consistently advises maintaining clean email lists and ensuring email content is relevant and not spammy. These factors heavily influence sender reputation and deliverability regardless of IP configuration.