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E-mail server parameters

Set up e-mail sending and receiving – incoming/outgoing servers as system BOs, connection security and OAuth2.

HOW-TO ADMINISTRATOR UPDATED: JUL 2026 APPLIES TO NUCLOS 4.2026.X

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From Nuclos 4.2025.3, e-mail sending and receiving are configured via the system BOs outgoing e-mail server and incoming e-mail server (instead of individual system parameters).

Configuring the e-mail server

Incoming e-mail server

Field	Meaning
Name	must be unique.
Order	without a server given, the active server with the lowest number is used.
Type	IMAP or POP3.
Server / port	host and port of the IMAP/POP3 service.
Connection security	None, SSL/TLS, STARTTLS.
Authentication	OAuth2 or Password.
Server directory	folder to read from (default INBOX).
Move deleted messages to	target folder for deleted messages.
Tenants	assign the configuration to a tenant (context on retrieval).
Test	test retrieval – preferably with a mailbox holding few messages.

Outgoing e-mail server

Field	Meaning
Name	must be unique.
Order	without a server given, the active server with the lowest number is used.
Server / port	host and port of the SMTP service.
Connection security	None, SSL/TLS, STARTTLS.
Authentication	None, OAuth2 or Password.
Sender address	address to send from.
Tenants	assign the configuration to a tenant (context on sending).
Test	sends a test e-mail to the given recipient.

OAuth2 (client credentials flow)

OAuth2 is supported for sending and receiving. As Nuclos acts as a backend service, the client credentials flow is used – after the initial setup by an administrator no further user interaction is needed.

Field	Meaning
Token endpoint	endpoint to obtain a valid token.
Client ID	unique identifier of the client.
Client secret	shared secret of the client.
Scopes	scope of the token.

Deprecated: legacy parameters

The former configuration via the system parameters SMTP …, POP3 … and IMAP … is deprecated and may be removed in a future release. New systems should use the system BOs.