`smtp://`¶

SMTP producer. Uses Go stdlib net/smtp + mime/multipart. For TLS-from-the-start endpoints use smtps://. For receive, see imap:// / imaps:// / pop3:// / pop3s://.

URI shape¶

smtp://host[:port]?from=…&to=…&username=…&password=…

host is the URI path segment (or ?host=…). Default port 587 (smtp). Default to, cc, etc. can be set on the URI; per-request headers override.

Parameters¶

Connection¶

Param	Type	Default	Description
`host`	string	from URI path	SMTP server host.
`port`	integer	`587`	SMTP server port.
`username`	string	—	SMTP AUTH username.
`password`	string	—	SMTP AUTH password.
`authMechanism`	enum	`plain`	`plain` (AUTH PLAIN) or `login` (AUTH LOGIN). Office 365 rejects PLAIN with `504 5.7.4` and requires `login`. Credentials are sent only over TLS/STARTTLS.
`connectionTimeout`	duration	`30s`	TCP dial timeout.

Header defaults (overridable per-message)¶

Param	Type	Default	Description
`from`	string	—	Default `From:` address.
`to`	string	—	Default `To:` (CSV).
`cc`	string	—	Default `Cc:` (CSV).
`bcc`	string	—	Default `Bcc:` (envelope-only).
`replyTo`	string	—	Default `Reply-To:` address.
`subject`	string	—	Default `Subject:`.
`contentType`	string	`text/plain; charset=UTF-8`	Default body content type.
`useInlineAttachments`	boolean	`false`	Build `multipart/related` so HTML body can reference `cid:<name>` images.
`alternativeBodyHeader`	string	`HelixMailAlternativeBody`	Header that supplies the plain-text alternative when the body is HTML.

TLS¶

Param	Type	Default	Description
`tls`	boolean	`false` (smtp), `true` (smtps)	Implicit TLS from connection start.
`starttls`	boolean	`false`	Opportunistic STARTTLS upgrade.
`tlsInsecure`	boolean	`false`	Skip certificate verification (testing only).
`tlsServerName`	string	—	SNI server name override.
`tlsCert` / `tlsKey` / `tlsCA`	string	—	Client cert + key + CA bundle.

Body shape¶

The In body becomes the message body. Set the message shape via the exchange:

Plain text: body is string or []byte; Content-Type defaults to text/plain; charset=UTF-8.
HTML: set the Content-Type header to text/html; charset=UTF-8. When HelixMailAlternativeBody is also set, the producer builds multipart/alternative (plain + HTML).
Attachments: set the Attachments header to map[string][]byte. The producer wraps the body in multipart/mixed.
Inline images (when useInlineAttachments=true): set InlineAttachments header to map[string][]byte. HTML body references each image as <img src="cid:<filename>">. Wraps in multipart/related.

Header conventions¶

Header	Direction
`HelixMailContentType`	Read
`HelixMailAlternativeBody`	Read
`HelixMailMessageId`	Written on success
Standard headers (`Subject`, `From`, `To`, `Cc`, `Bcc`, `Reply-To`)	Read
`Attachments` (map[string][]byte)	Read

Examples¶

Plain text¶

- to: smtp://mail.example.com:587?from=ops@example.com&username=ops&password=…&starttls=true
  # body: "Hello Helix!"   To header set on the exchange

Office 365 rejects AUTH PLAIN — use authMechanism=login over STARTTLS:

- to: "smtp://smtp.office365.com:587?from=svc@contoso.com&username=svc@contoso.com&password=${env:O365_PASSWORD}&authMechanism=login&starttls=true"
  # To / Subject set on the exchange; body is the message text.

HTML + plain alt¶

- to: smtp://mail.example.com?from=alerts@example.com
  # body: "<p>Hello</p>"
  # headers:
  #   Content-Type: text/html; charset=UTF-8
  #   HelixMailAlternativeBody: "Hello"

Attachment¶

- to: smtp://mail.example.com?from=ops@example.com
  # body: "Report attached."
  # headers:
  #   Attachments: { report.csv: [bytes] }

smtp://¶