email.generator.BytesGenerator

class email.generator.BytesGenerator(outfp, mangle_from_=True, maxheaderlen=78, *, policy=None)

The constructor for the BytesGenerator class takes a binary file-like object called outfp for an argument. outfp must support a write() method that accepts binary data.

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 beginning of the line. This is the only guaranteed portable way to avoid having such lines be mistaken for a Unix mailbox format envelope header separator (see WHY THE CONTENT-LENGTH FORMAT IS BAD for details). mangle_from_ defaults to True, but you might want to set this to False if you are not writing Unix mailbox format files.

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 split as defined in the Header class. Set to zero to disable header wrapping. The default is 78, as recommended (but not required) by RFC 2822.

The policy keyword specifies a policy object that controls a number of aspects of the generator’s operation. If no policy is specified, then the policy attached to the message object passed to flatten is used.

The other public BytesGenerator methods are:

flatten(msg, unixfrom=False, linesep=None)

Print the textual representation of the message object structure rooted at msg to the output file specified when the BytesGenerator instance was created. Subparts are visited depth-first and the resulting text will be properly MIME encoded. If the policy option cte_type is 8bit (the default), then any bytes with the high bit set in the original parsed message that have not been modified will be copied faithfully to the output. If cte_type is 7bit, the bytes will be converted as needed using an ASCII-compatible Content-Transfer-Encoding. In particular, RFC-invalid non-ASCII bytes in headers will be encoded using the MIME unknown-8bit character set, thus rendering them RFC-compliant.

Messages parsed with a Bytes parser that have a Content-Transfer-Encoding of 8bit will be reconstructed as 8bit if they have not been modified.

Optional unixfrom is a flag that forces the printing of the envelope header delimiter before the first RFC 2822 header of the root message object. If the root object has no envelope header, a standard one is crafted. By default, this is set to False to inhibit the printing of the envelope delimiter.

Note that for subparts, no envelope header is ever printed.

Optional linesep specifies the line separator character used to terminate lines in the output. If specified it overrides the value specified by the Generatoror msg‘s policy.

clone(fp)

Return an independent clone of this BytesGenerator instance with the exact same options.

write(s)

Write the string s to the underlying file object. s is encoded using the ASCII codec and written to the write method of the outfp outfp passed to the BytesGenerator‘s constructor. This provides just enough file-like API for BytesGenerator instances to be used in the print() function.