NewServer returns a MailServer struct given a listening address and a mail handler.

NewSingleServerSendMailer returns a MailSender offering outgoing SMTP functionality.

MailEnvelope describes the minimum information sent and received by a mail server.

MailServer contains the information necessary to run a server which receives and handles mail.

SingleServerSendMailer sends mails via one specified SMTP server.

MailSender allows simple mail sending.

Handler is a callback type for treating received mail.