End of an era at ExchangeDefender | ExchangeDefender [ Skip to content ](#main) [ ![ExchangeDefender](/assets/images/xd_logo_blue.png) ](/) Email Security ![Platform Overview](/assets/images/m-xd-pro.png)### ExchangeDefender PRO Enterprise-grade email security made simple for every business. [Sign Up](/sign-up) [Live Demo](/demo) [Email Security Stops spam, malware & phishing in real time. ](/email-security) [Encryption Secure your emails, attachments & sensitive data. ](/corporate-email-encryption) [Web File Sharing Easy, safe cloud file sharing with access control. ](/web-file-server) [Live Archive Locked-in email backup & continuity during outages. ](/livearchive-backup) [Emergency Inbox Keep email flowing without interruption if your provider fails. ](/inbox) [Spearphish Train your team with phishing simulations & risk tracking. ](/spearphishing) Managed Email ### Enterprise-Grade Managed Email Reliable, secure, and fully managed email operations for modern organizations. ![ExchangeDefender](/assets/images/managed_email_menu.png) [Microsoft365/Google Email Management Expert management and security for Microsoft 365 and Google Workspace email. ](/managed-email-operations) [AI Advisory Secure, practical AI consulting & implementation for SMBs. ](/management-ai) Company ### ExchangeDefender: 29+ Years of Trust We are a cybersecurity company focused on business email protection, with 29+ years of experience keeping organizations secure, connected, and resilient. ![ExchangeDefender](/assets/images/careers_1.png) [ About Us Learn our purpose, values, and the mission behind every decision. ](/about-us) [ Blog News, product updates and email security insights. ](/blog) [ Capabilities Discover the tech and expertise that keep your email secure around the clock ](/capabilities) [ Careers Be part of a team using modern tech to solve real threats and ship great work. ](/careers) [Partners](/partners) [Docs](/docs) [Contact Us](/contact) Talk to a Human Open menu Menu ---- Email Security [Email Security](/email-security) [Encryption](/corporate-email-encryption) [Web File Sharing](/web-file-server) [Live Archive](/livearchive-backup) [Inbox](/inbox) [Spearphish](/spearphishing) Managed Email [Microsoft365/Google Email Management](/managed-email-operations) [AI Advisory](/management-ai) Company [About Us](/about-us) [Blog](/blog) [Capabilities](/capabilities) [Careers](/careers) [Partners](/partners) [Docs](/docs) [Contact Us](/contact) Talk to a Human August 16, 2007 · [ExchangeDefender](https://www-preview.exchangedefender.com/blog?category=exchangedefender) End of an era at ExchangeDefender ================================= Dear Customers and Partners, I have just signed off on an implementation that in my mind is long overdue. For years ExchangeDefender processed messages from senders that did not have legitimate reverse DNS entries for their mail servers. As a major supporter of small business and a small business ourselves, we understand that at times it is difficult to appropriate enough funds to properly manage a complex IT infrastructure. As such, we have accepted messages from hosts that do not have valid PTR/reverse DNS because we are aware of how many small businesses rely on the unreliable and poorly configured appliances that generate real business email. Everything from copiers down to portable scanners now generates email of some sort, not to mention the many web sites and services. However, dealing with this problem over the past year has become impossible to sustain. The amount of worms and botnets launched from dialup, dynamic and even missing DNS has been on an exponential rise and we continue to receive a bulk of our mail from mail servers that would not be accepted as a relay anywhere else. While we want to do whatever we can to assure email delivery, it is simply not feasible to ignore the RFCs anymore. So, starting today, ExchangeDefender will require a valid DNS entry before accepting your messages. The mail will never be rejected but we will defer accepting it until you (or your IT consultant or your ISP) provide a valid PTR record / reverse DNS for your mail server. Should a message come in from a server that does not have valid reverse DNS you will get the following error: > 4.7.1 Access temporarily denied. ExchangeDefender requires you to have valid reverse DNS PTR record in order to send mail from \[IP\] This is a hard-coded network-wide setting that does not allow for any exceptions. The sender will be notified immediately and will have a chance to setup a PTR record and allow us to accept their mail. For help with how to setup and manage DNS please have the remote sender contact their ISP. This move will reduce the amount of SPAM you have to review each day and will reduce the number of worms and annoying SPAM messages you have been seeing over the past year or so. I again want to stress that we did not come to this decision lightly but based on the statistical breakdown of where most of the threats were emerging we had no choice but to defer connections from hosts that do not comply with the basic standards that govern the way mail is sent around the Internet. As always, thank you for your business and trusting us to keep your mailbox clean. Sincerely, Vlad Mazek, CEO, Own Web Now Corp. [ Previous post ExchangeDefender Delivery Alert August 15, 2007 ](https://www-preview.exchangedefender.com/blog/2007/08/exchangedefender-delivery-alert) [ Next post Loose e-mail in the cloud.. with diamonds (ExchangeDefender Mail Tracking) August 17, 2007 ](https://www-preview.exchangedefender.com/blog/2007/08/loose-e-mail-in-the-cloud-with-diamonds-exchangedefender-mail-tracking) Related Posts ------------- [ ![](https://storage.services.exchangedefender.network/exchangedefender-blog/blog/2026/04/xd10.png) 2 Apr ](https://www-preview.exchangedefender.com/blog/2026/04/announcing-exchangedefender-10)### [Announcing ExchangeDefender 10](https://www-preview.exchangedefender.com/blog/2026/04/announcing-exchangedefender-10) [Read more: Announcing ExchangeDefender 10](https://www-preview.exchangedefender.com/blog/2026/04/announcing-exchangedefender-10) [ ![](https://storage.services.exchangedefender.network/exchangedefender-blog/blog/2025/09/Top-7-IT-Solutions-Every-Small-Business-Needs-in-2025.jpg) 30 Sep ](https://www-preview.exchangedefender.com/blog/2025/09/top-7-it-solutions-every-small-business-needs-in-2025)### [Top 7 IT Solutions Every Small Business Needs in 2025](https://www-preview.exchangedefender.com/blog/2025/09/top-7-it-solutions-every-small-business-needs-in-2025) [Read more: Top 7 IT Solutions Every Small Business Needs in 2025](https://www-preview.exchangedefender.com/blog/2025/09/top-7-it-solutions-every-small-business-needs-in-2025) [ ![](https://storage.services.exchangedefender.network/exchangedefender-blog/blog/2025/09/Website-Active-Image-10.jpg) 23 Sep ](https://www-preview.exchangedefender.com/blog/2025/09/exchangedefender-rolls-out-advanced-reject-policies-for-safer-inboxes)### [ExchangeDefender Rolls Out Advanced 'Reject Policies' for Safer Inboxes](https://www-preview.exchangedefender.com/blog/2025/09/exchangedefender-rolls-out-advanced-reject-policies-for-safer-inboxes) [Read more: ExchangeDefender Rolls Out Advanced 'Reject Policies' for Safer Inboxes](https://www-preview.exchangedefender.com/blog/2025/09/exchangedefender-rolls-out-advanced-reject-policies-for-safer-inboxes) Search the blog Search Recent Posts ------------ - [ExchangeDefender New UI is Live](https://www-preview.exchangedefender.com/blog/2026/05/exchangedefender-new-ui-is-live) - [Announcing ExchangeDefender 10](https://www-preview.exchangedefender.com/blog/2026/04/announcing-exchangedefender-10) - [Merry Christmas](https://www-preview.exchangedefender.com/blog/2025/12/merry-christmas) - [Why IoT Devices Are a Hidden Security Risk for Your Business](https://www-preview.exchangedefender.com/blog/2025/11/why-iot-devices-are-a-hidden-security-risk-for-your-business) - [Top 5 IT Problems Small Businesses Face in 2025 — and How to Fix Them](https://www-preview.exchangedefender.com/blog/2025/10/top-5-it-problems-small-businesses-face-in-2025-and-how-to-fix-them) Categories ---------- - [Archiving](https://www-preview.exchangedefender.com/blog?category=archiving) (21) - [Business Continuity](https://www-preview.exchangedefender.com/blog?category=business-continuity) (13) - [Compliance](https://www-preview.exchangedefender.com/blog?category=compliance) (8) - 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