Module Sendmail_lwt

Sending an email with lwt.

This module lets you send emails directly (sendmail) or via an authority (submit).

The first function is the simplest (and recommended), sending an email directly to a destination on port 25 (if port is not specified). By default, we always try to communicate with STARTTLS if the service allows it. The user can specify a TLS configuration or a specific X509.Authenticator.t (in particular to accept self-signed certificates). The user can also specify authentication, which is generally not required for this type of SMTP service. Note that the implementation will never attempt authentication if STARTTLS is not available - and will fail.

The second function allows you to submit an email to an authority so that the authority can send your email to its destinations. By default, we use port 465 on which we directly use TLS (and not STARTTLS) to encrypt all communications between you and the service. You can specify port 587 (if the service on 465 is not available) which this time will use STARTTLS to encrypt the communication. This service often requires authentication (so that you can prove that you can use this authority). Like sendmail, if authentication is required without the communication being encrypted, we will fail.

The second function allows you to send an email under an identity other than your own. In fact, when you want to send an email using the identity foo@gmail.com, you need to authenticate yourself and send the email to smtp.gmail.com so that this service can in turn send your email to the destinations (adding several pieces of information such as a DKIM signature).