One of the most common tasks is to generate the flat text of the email
message represented by a message object tree. You will need to do
this if you want to send your message via the smtplib
module or the nntplib module, or print the message on the
console. Taking a message object tree and producing a flat text
document is the job of the Generator class.
Again, as with the email.Parser module, you aren't limited
to the functionality of the bundled generator; you could write one
from scratch yourself. However the bundled generator knows how to
generate most email in a standards-compliant way, should handle MIME
and non-MIME email messages just fine, and is designed so that the
transformation from flat text, to an object tree via the
and back to flat text, is idempotent (the input is identical to the
Here are the public methods of the Generator class:
The constructor for the Generator class takes a file-like
object called outfp for an argument. outfp must support
the write() method and be usable as the output file in a
Python 2.0 extended print statement.
Optional mangle_from_ is a flag that, when true, puts a ">"character in front of any line in the body that starts exactly as
"From " (i.e. From followed by a space at the front of the
line). This is the only guaranteed portable way to avoid having such
lines be mistaken for Unix-From headers (see
WHY THE CONTENT-LENGTH FORMAT IS BAD
Optional maxheaderlen specifies the longest length for a
non-continued header. When a header line is longer than
maxheaderlen (in characters, with tabs expanded to 8 spaces),
the header will be broken on semicolons and continued as per
RFC 2822. If no semicolon is found, then the header is left alone.
Set to zero to disable wrapping headers. Default is 78, as
recommended (but not required) by RFC 2822.
Print the textual representation of the message object tree rooted at
msg to the output file specified when the Generator
instance was created. Sub-objects are visited depth-first and the
resulting text will be properly MIME encoded.
Optional unixfrom is a flag that forces the printing of the
Unix-From (a.k.a. envelope header or From_ header)
delimiter before the first RFC 2822 header of the root message
object. If the root object has no Unix-From header, a standard
one is crafted. By default, this is set to 0 to inhibit the printing
of the Unix-From delimiter.
Note that for sub-objects, no Unix-From header is ever printed.
Write the string s to the underlying file object,
i.e. outfp passed to Generator's constructor. This
provides just enough file-like API for Generator instances to
be used in extended print statements.
As a convenience, see the methods Message.as_string() and
str(aMessage), a.k.a. Message.__str__(), which
simplify the generation of a formatted string representation of a
message object. For more detail, see email.Message.