Reference

CLI arguments

Flag	Default	Description
--from-address	required	From address
--to-address	required	To address
--smtp-username	SMTP_USERNAME	SMTP username; omit both to skip AUTH
--smtp-password	SMTP_PASSWORD	SMTP password; omit both to skip AUTH
--smtp-server	required	SMTP hostname
--smtp-port	25	SMTP port (1–65535)
--timeout	10	Socket timeout in seconds
--tls	off	Implicit TLS (SMTP_SSL)
--no-starttls	off	Do not require STARTTLS
--subject	Simple test message	Message subject
--body	built-in body	Plain-text body
--verbose	off	Log SMTP steps without protocol payloads
--version	—	Print the package version and exit

--timeout must be greater than 0 when set. --tls never issues STARTTLS. Without --tls or --no-starttls, STARTTLS is required.

Exit codes

Code	When
0	Help, version, or the test message was accepted
1	Invalid arguments, mismatched credentials, or the send failed

Library

Name	Meaning
send_test_message	Connect, optionally authenticate, and send one test message
SmtpTestResult	Frozen result: ok, to_address, detail, smtp_code
smtp_code	SMTP status code on failure, or None
build_test_message	Build the MIME EmailMessage with Date and Message-ID
DEFAULT_PORT	Default SMTP port (25)
DEFAULT_TIMEOUT	Default socket timeout (10)
DEFAULT_SUBJECT	Default message subject
DEFAULT_BODY	Default plain-text body
get_version()	Return the package version string

send_test_message never puts the password into detail or debug logs. Socket, timeout, TLS, authentication, and SMTP reply failures return ok=False instead of raising. ValueError is raised for a bad port, a non-positive timeout, or a username without a password (or the reverse). SMTPNotSupportedError and other SMTPException subclasses are returned as failures.