Summary
The consensus suggests that the '[VI-1]' filter is linked to Synacor, with Synchronoss potentially providing the underlying technology. VadeSecure is also a possible component, hinted at by the 'V' in the code. However, identifying the exact source is complex, as ISPs often customize filtering solutions. Analysis of email headers, SMTP banners, and bounce messages is crucial. Engaging support teams and ensuring proper email authentication (SPF, DKIM, DMARC) and maintaining a good IP reputation are also essential for deliverability.
Key findings
- Primary Suspects: Synacor is strongly implicated, potentially utilizing technology from Synchronoss, as the source of the '[VI-1]' filter.
- VadeSecure Involvement: VadeSecure's technology may play a role, indicated by the 'V' in the filter code.
- Customization Challenges: The unique configurations of filtering solutions by individual ISPs make it difficult to pinpoint the exact responsible party.
- Regional association: The '[VI-1]' filter may be more commonly used by cable companies in Russia and Eastern Europe
Key considerations
- Header Examination: Thoroughly analyze email headers and SMTP banners to uncover patterns and vendor information.
- Support Engagement: Contact both your email provider and the recipient's ISP to investigate the blocking.
- Authentication Protocol Setup: Implement and verify SPF, DKIM, and DMARC records.
- Reputation Management: Proactively monitor and maintain your IP and domain reputation.
- Look at the bounce message: Pay attention to the bounce messages and work with the sender support teams to review any blocks.
What email marketers say
9 marketer opinions
Identifying the filter responsible for the '[VI-1]' block requires a multi-faceted approach. While there's no definitive answer, several sources point towards Synchronoss and Synacor, companies providing email solutions to ISPs, as potential candidates. The 'V' in '[VI-1]' might refer to VadeSecure, a company specializing in email security. Experts recommend analyzing email headers, bounce messages, and SMTP banners for patterns, performing reverse DNS lookups on blocking servers, and contacting support teams. Implementing proper email authentication (SPF, DKIM, DMARC) and maintaining good IP reputation are also crucial for deliverability. It's important to recognize that ISPs often customize their filtering solutions, making specific filter identification challenging.
Key opinions
- Possible Vendor: Synchronoss and Synacor are frequently mentioned as potential companies responsible for implementing the '[VI-1]' filter, given their role in providing email solutions to ISPs.
- VadeSecure Connection: The 'V' in '[VI-1]' may potentially refer to VadeSecure, an email security company. It is also possible this is being used via one of the other providers.
- Customization Complexity: ISPs often customize their email filtering solutions, which makes pinpointing the specific filter and vendor behind '[VI-1]' very difficult.
Key considerations
- Header Analysis: Perform a thorough analysis of email headers and bounce messages to identify patterns and vendor-specific identifiers.
- Reverse DNS: Conduct reverse DNS lookups on the blocking server's IP address to potentially reveal the service provider's name.
- Contact Support: Reach out to the support teams of both the sender and the recipient's email providers for assistance in diagnosing the issue.
- Email Authentication: Ensure proper implementation of email authentication protocols (SPF, DKIM, DMARC) to improve email deliverability.
- Monitor Reputation: Maintaining good IP and domain reputation is important for avoiding email blocks. Monitor listing on blocklists and engage with blocklist operators if needed.
Marketer view
Marketer from Email Geeks suggests that Synacor might be the filter using '[VI-1]' when blocking mail, and that the 'V' might refer to Vade.
8 Aug 2022 - Email Geeks
Marketer view
Email marketer from emailadmin.форум shares that the '[VI-1]' filter is commonly associated with email services used by cable companies in Russia and Eastern Europe. They believe Synchronoss provides the infrastructure for some of these services, but direct confirmation is difficult.
21 Apr 2024 - emailadmin.форум
What the experts say
3 expert opinions
The '[VI-1]' filter appears to be associated with Synacor, with the underlying technology potentially originating from Synchronoss. While a direct solution isn't readily available, experts recommend a detailed analysis of email headers and engaging with support teams to understand the blocking reason. This will probably require contacting the ISP and email provider.
Key opinions
- Synacor Association: The '[VI-1]' filter is likely implemented by Synacor, with MX records pointing to their infrastructure.
- Synchronoss Origin: The underlying technology for the filter may be linked to Synchronoss.
- Lack of Direct Solution: There isn't a straightforward solution; resolving the blocking requires investigation and collaboration with email providers.
Key considerations
- Analyze Headers: Carefully examine email headers and bounce messages for clues about the filtering process and responsible vendor.
- Engage Support: Contact the support teams of both your email provider and the recipient's ISP to investigate the blocking issue.
Expert view
Expert from Email Geeks explains that the filter '[VI-1]' is being sent by an MX owned by Synacor and under the covers appears to be coming out of <https://synchronoss.com>.
22 Jan 2022 - Email Geeks
Expert view
Expert from Word to the Wise shares how you can find the source of filters. Laura recommends reading the block message and looking at patterns in the headers that might reveal which vendor is responsible for the blocks. Requires deeper research and potentially engaging with the ISP or email provider experiencing the block.
12 Mar 2022 - Word to the Wise
What the documentation says
6 technical articles
While the specific '[VI-1]' filter remains unidentified, the provided documentation highlights the complex ecosystem of email security and deliverability. Synchronoss, VadeSecure, and MessageSystems offer services and platforms used by ISPs, potentially incorporating the filter. The RFC documentation suggests '[VI-1]' could be a vendor-specific enhanced status code. Proper implementation of DKIM/DMARC and maintaining a good IP reputation, as emphasized by DKIM.org and Spamhaus, are crucial for avoiding blocks, regardless of the specific filter in use.
Key findings
- Service Provider Involvement: Synchronoss, VadeSecure, and MessageSystems are potential players as they provide email infrastructure and security solutions to ISPs.
- Vendor-Specific Code: '[VI-1]' might be a vendor-specific enhanced status code used within SMTP responses, but this needs further confirmation.
- Best Practices Importance: Good email authentication (DKIM/DMARC) and a clean IP reputation are essential for deliverability, regardless of the specific filters used.
Key considerations
- Authentication Protocols: Verify and properly configure SPF, DKIM, and DMARC records for your sending domain.
- Reputation Monitoring: Continuously monitor your IP and domain reputation using tools like Spamhaus and address any issues promptly.
- Enhanced Status Codes: Examine the full SMTP enhanced status code provided in bounce messages for more detailed information about the reason for the block.
Technical article
Documentation from Synchronoss confirms they offer email platform services to telecommunications companies and ISPs, which include security and filtering capabilities. It does not specifically mention '[VI-1]', but highlights their comprehensive email management solutions.
8 Feb 2024 - Synchronoss
Technical article
Documentation from MessageSystems explains that Momentum (their MTA) can integrate with various filtering solutions. It doesn't specify '[VI-1]', but confirms its platform's flexibility in incorporating third-party or custom filters.
20 Aug 2021 - MessageSystems
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