Terence Luk: Rerouting outbound SMTP mail through Exchange 2016 Send Connectors from Exchange 2010 fails with: 451 4.4.0 Primary target IP address responded with: “421 4.3.2 Service not available.”
Clint Boessen's Blog: Exchange 2013 421 4.3.2 Service not active
T-Solve Technology Commentary: 421 4.3.2 Service not available, closing transmission channel on SBS 2008 - not receiving external email
How to Resolve Error 421 Service Not Available with FTP
SBS - No Incoming Mail '421 4.3.2 Service not available' | PeteNetLive
Exchange 2016 sent mails go to drafts - 421 4.3.2 Service not active - ITXPerience
The transport failed to connect to the server - Qlik Community - 1080996
Monitoring SMTP with Wire Data from Reveal(x)
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How to fix [Message=421 4.3.2 Service not available] error? -
421 4.3.2 Service not active - Exchange 2019 – IT-Helper
![How to fix [Message=421 4.3.2 Service not available] error?? - Microsoft Q&A](https://learn-attachment.microsoft.com/api/attachments/31219-wireshark-packet-capture-2020-10-09-101207.png?platform=QnA "How to fix [Message=421 4.3.2 Service not available] error?? - Microsoft Q&A")
How to fix [Message=421 4.3.2 Service not available] error?? - Microsoft Q&A
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How to fix [Message=421 4.3.2 Service not available] error? -
Exchange Server 2013 - Mail Flow and Secure Messaging forum
James Rogers: Exchange 2013: 421 4.3.2 Service not available
February | 2016 | Exchange-Fix
Exchange - Mailserver - Fehlermeldung - 421 4.3.2 Service not available - TASTE-OF-IT
Clint Boessen's Blog: Exchange 2013 421 4.3.2 Service not active
telnet to smtp . 421 4.3.2 Service not available Connection closed by foreign host - YouTube
T-Solve Technology Commentary: 421 4.3.2 Service not available, closing transmission channel on SBS 2008 - not receiving external email
James Rogers: Exchange 2013: 421 4.3.2 Service not available
Exchange 2013: SMTP 421 4.3.2 Service not active - Frankys Web
Exchange 2013: SMTP 421 4.3.2 Service not active - Frankys Web
