Mail

WordPress sends mail through PHP's mail(). The image routes that through msmtp to an SMTP relay, configured from the chart's values through environment variables. No mail plugin is needed and nothing is written to the database.

smtpHost: smtp.example.com
smtpPort: "587"
smtpUser: wordpress@example.com
smtpExistingSecret: my-smtp-secret   # key: smtp-password
smtpProtocol: tls
smtpFromEmail: wordpress@example.com
smtpFromName: Example Blog

Without smtpHost every send fails, with a line in the container log: [mail error] SMTP_HOST is not defined.

Parameters

Parameter	Description	Default
smtpHost	SMTP relay host	""
smtpPort	SMTP relay port. Empty leaves it to msmtp: 25, or 465 with smtpProtocol: ssl	""
smtpUser	SMTP user name. Authentication switches on as soon as a user or a password is set	""
smtpPassword	SMTP password	""
smtpExistingSecret	Name of a Secret with the password under the key smtp-password; smtpPassword is then ignored	""
smtpProtocol	Connection security, see below	""
smtpFromEmail	Sender address, see below	""
smtpFromName	Display name for the sender address; requires smtpFromEmail	""

Connection security

smtpProtocol	Connection
tls	STARTTLS; relays usually offer it on port 587, which smtpPort has to name
ssl	implicit TLS (smtps), port 465
none	unencrypted, even with credentials
"" (default)	unencrypted without credentials; STARTTLS as soon as smtpUser or a password is set

Credentials set through these values are therefore not sent over an unencrypted connection unless none says so. Set none only for an internal relay that authenticates but offers no TLS. Any other value fails the render.

The empty default looks at smtpUser, smtpPassword and smtpExistingSecret only. Credentials that reach the container another way, as SMTP_USER or SMTP_PASSWORD in extraEnvVars, extraEnvVarsCM or extraEnvVarsSecret, switch nothing on: set smtpProtocol: tls or ssl next to them.

An entry named SMTP_TLS in extraEnvVars takes precedence: the chart then renders none of its own, whatever smtpProtocol and the credentials say. A variable of that name from extraEnvVarsCM or extraEnvVarsSecret does not, because the chart cannot see into those and the container's own variable wins over them. Set the connection security in one place, with smtpProtocol where that is possible.

Sender address

With smtpFromEmail set, the address becomes the envelope sender and replaces the message's From header on its way into msmtp. The rewriting happens in the transport; no code is added to WordPress. Relays that tie the sender to the authenticated identity need it: Office 365, for one, rejects a message whose From header differs from the account.

smtpFromName adds a display name (Name <address>); names outside ASCII are encoded per RFC 2047. Setting it without smtpFromEmail fails the render.

Left empty, envelope and header stay what WordPress wrote, by default wordpress@<site host>.