MIME Entities
Everything that forms part of a Message is called a MIME Entity. All MIME entities in Swift Mailer share a common set of features. There are various types of MIME entity that serve different purposes such as Attachments and MIME parts.
An e-mail message is made up of several relatively simple entities that are combined in different ways to achieve different results. All of these entities have the same fundamental outline but serve a different purpose. The Message itself can be defined as a MIME entity, an Attachment is a MIME entity, all MIME parts are MIME entities – and so on…
Header-Name: A header value Other-Header: Another value The body content itself
The Headers of a MIME entity, and its body must conform to some strict standards defined by various RFC documents. Swift Mailer ensures that these specifications are followed by using various types of object, including Encoders and different Header types to generate the entity.
Each MIME component implements the base Swift_Mime_MimeEntity interface, which offers methods for retrieving Headers, adding new Headers, changing the Encoder, updating the body and so on…
All MIME entities have one Header in common – the Content-Type Header, updated with the entity's setContentType() method.