Domino agent - Remote server is not a known TCP/IP host
I have a Domino development server I can't get web-based emails to send from. The error I'm getting is "The remote server is not a known TCP/IP host". The server works fine for Notes based emails, but I'm generating emails from LotusScript in an app, and they are not sending. This server was recently created (Dom 8.5.3).
I have the server sending email directly to the Internet on all location documents (for Notes client).
Answer
See IBM Technote #1099632 "Notes/Domino background agent fails to send mail; Errors may occur in logs":
These errors may be caused by an improper entry for the Mail Server field in the Server document in the Domino Directory (public Name and Address Book).
The errors may also be caused by a server configuration or TCPIP issue. For example, if the Network Address field for a TCPIP port contains either an incorrect host name or an IP address, the errors occur. If the DNS is not working correctly the errors will occur.
The issue was noted in at least one case because the server was resolvable by IP address but not resolvable by Fully Qualified Host Name (FQHN). The IP address was listed in the Net Address field of the Server document but this error message still appeared. To resolve this issue, update the DNS servers to point the FQHN to the correct server. In one case it was discovered that the particular Domino server was not listed in its own host table. Update the host file of the server with the FQHN pointing to its own IP or localhost address.
The Technote also provides steps to troubleshoot the issue.
Also, you can enable some debugging to determine where the problem surfaces.
For outbound SMTP-related issues, enable the debug parameters below on the server to capture data:
CONSOLE_LOG_ENABLED=1
DEBUG_THREADID=1
debug_show_timeout=1
debug_capture_timeout=1
SMTPClientDebug=1
See Collecting data for Domino SMTP mail routing issues for more details on that