![Field Report: Cisco and Exchange woes. 451 5.7.3 Cannot achieve Exchange Server authentication. Telnet fails with 200***** | Jude's Blog Field Report: Cisco and Exchange woes. 451 5.7.3 Cannot achieve Exchange Server authentication. Telnet fails with 200***** | Jude's Blog](https://judeperera.files.wordpress.com/2016/11/env.png?w=730)
Field Report: Cisco and Exchange woes. 451 5.7.3 Cannot achieve Exchange Server authentication. Telnet fails with 200***** | Jude's Blog
![451 4.4.0 DNS query failed. The error was: SMTPSEND.DNS.NonExistentDomain; nonexistent domain « MSExchangeGuru.com 451 4.4.0 DNS query failed. The error was: SMTPSEND.DNS.NonExistentDomain; nonexistent domain « MSExchangeGuru.com](https://msexchangeguru.com/wp-content/uploads/2013/11/112413_0211_451440DNSq1.png)
451 4.4.0 DNS query failed. The error was: SMTPSEND.DNS.NonExistentDomain; nonexistent domain « MSExchangeGuru.com
![FAQ 000163 - SMTP Error 451 5.7.3 Cannot achieve Exchange Server authentication - Exchangemaster GmbH FAQ 000163 - SMTP Error 451 5.7.3 Cannot achieve Exchange Server authentication - Exchangemaster GmbH](https://www.exchangemaster.ch/wp-content/uploads/2018/11/FAQ000163-02.jpg)
FAQ 000163 - SMTP Error 451 5.7.3 Cannot achieve Exchange Server authentication - Exchangemaster GmbH
![FAQ 000163 - SMTP Error 451 5.7.3 Cannot achieve Exchange Server authentication - Exchangemaster GmbH FAQ 000163 - SMTP Error 451 5.7.3 Cannot achieve Exchange Server authentication - Exchangemaster GmbH](https://www.exchangemaster.ch/wp-content/uploads/2018/11/FAQ000163-01.jpg)
FAQ 000163 - SMTP Error 451 5.7.3 Cannot achieve Exchange Server authentication - Exchangemaster GmbH
![FAQ 000163 - SMTP Error 451 5.7.3 Cannot achieve Exchange Server authentication - Exchangemaster GmbH FAQ 000163 - SMTP Error 451 5.7.3 Cannot achieve Exchange Server authentication - Exchangemaster GmbH](https://www.exchangemaster.ch/wp-content/uploads/2018/11/FAQ000163-04.jpg)
FAQ 000163 - SMTP Error 451 5.7.3 Cannot achieve Exchange Server authentication - Exchangemaster GmbH
![Error: "Send test email message: The server responded: 550 5.7.1 Authentication." When Setting up POP3 and IMAP Account in Outlook – KerioConnect Support Error: "Send test email message: The server responded: 550 5.7.1 Authentication." When Setting up POP3 and IMAP Account in Outlook – KerioConnect Support](https://support.kerioconnect.gfi.com/hc/article_attachments/360014267700/2019-08-12_15-24-22.png)
Error: "Send test email message: The server responded: 550 5.7.1 Authentication." When Setting up POP3 and IMAP Account in Outlook – KerioConnect Support
![451 4.4 0 primary target ip address responded with 421 4.4 2 connection dropped due to socket error - Microsoft Q&A 451 4.4 0 primary target ip address responded with 421 4.4 2 connection dropped due to socket error - Microsoft Q&A](https://learn.microsoft.com/api/attachments/91008-image.png?platform=QnA)
451 4.4 0 primary target ip address responded with 421 4.4 2 connection dropped due to socket error - Microsoft Q&A
![Clint Boessen's Blog: 451 4.4.0 Primary target IP address responded with: " 451 5.7.3 Cannot achieve Exchange Server authentication." Clint Boessen's Blog: 451 4.4.0 Primary target IP address responded with: " 451 5.7.3 Cannot achieve Exchange Server authentication."](http://4.bp.blogspot.com/-AjZ7fl_dqe0/TvwLB19G2TI/AAAAAAAAByc/OVeZXVDL6-0/s1600/receiveconnector.png)
Clint Boessen's Blog: 451 4.4.0 Primary target IP address responded with: " 451 5.7.3 Cannot achieve Exchange Server authentication."
![Exchange 2010 Queue 451 440 Primary target IP address responded with:451 5.7.3 Cannot achieve Exchange Server authentication Exchange 2010 Queue 451 440 Primary target IP address responded with:451 5.7.3 Cannot achieve Exchange Server authentication](http://www.techieshelp.com/wp-content/uploads/2012/02/exchange-2003-smtp-authenticaton.png)
Exchange 2010 Queue 451 440 Primary target IP address responded with:451 5.7.3 Cannot achieve Exchange Server authentication
![FAQ 000163 - SMTP Error 451 5.7.3 Cannot achieve Exchange Server authentication - Exchangemaster GmbH FAQ 000163 - SMTP Error 451 5.7.3 Cannot achieve Exchange Server authentication - Exchangemaster GmbH](https://www.exchangemaster.ch/wp-content/uploads/2018/11/FAQ000163-03.jpg)