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#1: MIME coding for SMTP

Posted on 2008-04-16 17:18:22 by florin.barbalau

Hello,

I try to find the answer to a question regarding the number of bits
used for MIME encoding when used for SMTP.
Is it 8-bit or 7-bit?

thanks

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#2: Re: MIME coding for SMTP

Posted on 2008-04-16 17:35:35 by gtaylor

On 04/16/08 10:18, florin.barbalau@gmail.com wrote:
> I try to find the answer to a question regarding the number of bits
> used for MIME encoding when used for SMTP. Is it 8-bit or 7-bit?

If you are wondering about the ASCII data traveling between SMTP servers
it depends on if you are using the 8BITMIME SMTP extension or not. If
you are not then all your SMTP traffic should be 7 bit. If you are
using the 8BITMIME SMTP extension then you can send 8 bit data in the
SMTP transaction.

If you are wondering about how to MIME encode something in to a message
(not having any thing to do with SMTP), that is different.



Grant. . . .

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#3: Re: MIME coding for SMTP

Posted on 2008-04-16 17:57:35 by florin.barbalau

On Apr 16, 4:35 pm, Grant Taylor <gtay...@riverviewtech.net> wrote:
> On 04/16/08 10:18, florin.barba...@gmail.com wrote:
>
> > I try to find the answer to a question regarding the number of bits
> > used for MIME encoding when used for SMTP. Is it 8-bit or 7-bit?
>
> If you are wondering about the ASCII data traveling between SMTP servers
> it depends on if you are using the 8BITMIME SMTP extension or not. If
> you are not then all your SMTP traffic should be 7 bit. If you are
> using the 8BITMIME SMTP extension then you can send 8 bit data in the
> SMTP transaction.
>
> If you are wondering about how to MIME encode something in to a message
> (not having any thing to do with SMTP), that is different.
>
> Grant. . . .

I think 8BITMIME has nothing to do with MIME since it's an extension
of SMTP.
So the answer would 7-bit because I was interested in MIME format used
in the context of SMTP.
I looked on wikipedia and it looks even strange; it seems that for
base64 encoding (used by MIME) only six bits are used (64 distinct
values) ?
http://en.wikipedia.org/wiki/Base64#Example

Do you know what encoding is used in the SMTP context?

thanks
Florin

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#4: Re: MIME coding for SMTP

Posted on 2008-04-16 18:58:05 by gtaylor

On 04/16/08 10:57, florin.barbalau@gmail.com wrote:
> I think 8BITMIME has nothing to do with MIME since it's an extension
> of SMTP. So the answer would 7-bit because I was interested in MIME
> format used in the context of SMTP. I looked on wikipedia and it
> looks even strange; it seems that for base64 encoding (used by MIME)
> only six bits are used (64 distinct values) ?
> http://en.wikipedia.org/wiki/Base64#Example

....

> Do you know what encoding is used in the SMTP context?

With out the (poorly named(?)) 8BITMIME SMTP extension the SMTP
transaction is 7 bit ASCII. There is no ""encoding per say in SMTP.
SMTP is used to transfer 7 bit ASCII from one point to another. What
that 7 bit ASCII is is irrelevant to SMTP. You can use UU encoding or
MIME or what ever you want to encode things so that it is safe to send
in the 7 bit ASCII environment of SMTP (with out the 8BITMIME SMTP
extension).

The 8BITMIME SMTP extension is a ""feature that has been added to SMTP
to make it safe to carry 8 bit data in the SMTP environment. Again,
this environment does not care what is being carried so long as it is
valid for the environment.

Base64 encoding is a way to encode something down to something that is
safe to carry in the SMTP environment. Base64 encoding is probably the
most widely used and prevalent encoding system at present. However this
has nothing to do with what SMTP can or can not carry other than the
fact that it is used to convert something that is (likely) not safe to
something that is safe.



Grant. . . .

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