SendMail

sends mail consisting of body to the address specified by $WolframID.

SendMail[{"subject"}]

sends mail with the specified subject and no body.

SendMail[{"subject",body}]

sends mail with the specified subject and body.

SendMail[{"subject",body,att}]

sends mail with the attachment or attachments att.

SendMail["to",content]

sends mail to the specified To: address.

SendMail[{"to₁","to₂",…},content]

sends mail to multiple To: addresses.

SendMail[{{"to₁",…},{"cc₁",…}},content]

includes the cc_i as Cc: addresses.

SendMail[{{"to₁",…},{"cc₁",…},{"bcc₁",…}},content]

also includes the bcc_i as Bcc: addresses.

sends mail with elements specified in the association assoc.

Details and Options

Email addresses are given as strings.
The message body can be a string, an expression, or a list of expressions.
SendMail automatically embeds graphics and typeset expressions as raster image files. It embeds sounds as audio files. It also embeds symbolic XML as XML files.
SendMail uses appropriate encodings to handle any special characters that appear in a message.
On desktop systems, SendMail requires certain user mail settings. These can be defined through Preferences ▶ Internet & Mail ▶ Mail Settings in the notebook front end or by using SetOptions[SendMail,MailSettings]. SendMail will attempt to send email via the Wolfram Cloud if these settings have not been provided. »
In the Wolfram Cloud, emails are always relayed from the Wolfram Cloud server.
In SendMail[assoc], the association assoc can include the following basic elements:

"To"	{}	email addresses of primary recipients
"Cc"	{}	email addresses of secondary recipients
"Bcc"	{}	email addresses of hidden recipients
"Subject"	None	message subject line
"Body"	None	message body
"AttachedExpressions"	{}	expressions to send as attachments
"AttachedFiles"	{}	files to send as attachments

The association assoc can contain the following additional elements, which can also be given in the setting for the option MailSettings:

"AutoBcc"	None	automatic hidden recipients
"AutoCc"	None	automatic secondary recipients
"FromAddress"	Automatic	sender's email address
"FromName"	None	sender's full name
"ReplyTo"	None	suggested address for replies
"ReplyToMessageID"	None	ID of message to which this replies
"Signature"	None	text to be appended at the end of body

The following elements related to the mail connection can also be given in the association assoc, and in the settings for MailSettings:

"EncryptionProtocol"	None	email encryption protocol
"Password"	Automatic	user password
"PortNumber"	Automatic	server port number or numbers
"Server"	Automatic	server host name or IP address
"ServerAuthentication"	Automatic	whether and how to verify server certificates
"UserName"	$UserName	user login name

Possible settings for "EncryptionProtocol" include "SSL", "StartTLS", "TLS", and None.
"Password" is typically set to None if no password authentication is required, or to Automatic if the password is to be entered in an interactive dialog. The password can also be given as a plain text string.
Email credentials can be optionally stored via the "Password" interactive dialog. The credentials are encrypted using keys stored on your computer's hard drive. The encrypted credentials will be transmitted to the Wolfram Cloud and may only be accessed after you have authenticated using your Wolfram ID.
SendMail has the following options:
MailAddressValidation Automatic function for address validation

MailSettings Automatic an association of mail settings
The setting for MailAddressValidation is applied to all sender and recipient email addresses. If validation fails for any address, SendMail will not send any message.
SendMail returns a unique message identification string upon success and a Failure object otherwise.