On 18/08/2016 15:10, John Levine wrote:
not want compression at all. SMTP has different problems than IMAP,
which I think simple compression will not fix: Submit sees a single
message per connection, plain SMTP sees mostly spam. Why implement
I think the motivation is people sending around large documents in
formats like Word and Excel. Pictures and videos aren't very
compressible, but they're base64 encoded so compressing that tends to
get you back to the original size.
DOCX and XLSX formats are compressed as well. (They're basically ZIP
archives of XML & binary data)
So, you can't further compress those, and you can't further compress
pictures and videos.
Pretty much the only common things you can compress are PDF files. OK
some people still use DOC & XLS formats (even though they were replaced
9 years ago), but they're (hopefully) becoming less popular to send by
email because they can contain macros which DOCX and XLSX files can't,
so are a common malware vector.
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