MakeAttachmentHeader is a helper function that returns a textproto.MIMEHeader tailored for attachments, primarily email.

New returns a new instance of Mailer.

BaseTPL is the name of the base template.

ContentTpl is the name of the compiled message.

CampaignMessage represents an instance of campaign message to be pushed out, specific to a subscriber, via the campaign's messenger.

CampStats contains campaign stats like per minute send rate.

Config has parameters for configuring the manager.

Manager handles the scheduling, processing, and queuing of campaigns and message pushes.

Messenger is an interface for a generic messaging backend, for instance, e-mail, SMS etc.

Store represents a data backend, such as a database, that provides subscriber and campaign records.