Programming Python, 3rd Edition

email: Parsing and Composing Mails

The second edition of this book used a handful of standard library modules (rfc822, StringIO, and more) to parse the contents of messages, and simple text processing to compose them. Additionally, that edition included a section on extracting and decoding attached parts of a message using modules such as mhlib, mimetools, and base64.

Those tools are still available, but were, frankly, a bit clumsy and error-prone. Parsing attachments from messages, for example, was tricky, and composing even basic messages was tedious (in fact, an early printing of the prior edition contained a potential bug, because I forgot one \n character in a complex string formatting operation). Adding attachments to sent messages wasn’t even attempted, due to the complexity of the formatting involved.

Luckily, things are much simpler today. Since the second edition, Python has sprouted a new email package—a powerful collection of tools that automate most of the work behind parsing and composing email messages. This module gives us an object-based message interface and handles all the textual message structure details, both analyzing and creating it. Not only does this eliminate a whole class of potential bugs, it also promotes more advanced mail processing.

Things like attachments, for instance, become accessible to mere mortals (and authors with limited book real estate). In fact, the entire section on manual attachment parsing and decoding has been deleted in this edition—it’s ...