Sending Email Messages

To send an email message, you call the API of the Mail service. The outgoing message has a sender address (“From”), one or more recipients (“To,” “Cc,” or “Bcc”), a subject, a message body, and optional file attachments.

An email message can contain a limited set of message headers, which are understood by mail servers and clients. The headers an app can set are restricted to prevent the service from being abused to send forged messages. (See the official documentation for the current list of allowed headers.) The Mail service attaches additional headers to the message, such as the date and time the message is sent.

You can specify a multipart message body, such as to include both plain text and HTML versions of the message, and to include attachments. The total size of the message, including all headers and attachments, cannot exceed 10 megabytes.