Message Size
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... decline to accept a message (perhaps temporarily) based on the
client's estimate of the message size.
...
... which the server may indicate to the client that it is or is not
willing to accept the message based on the declared message size and
whereby a server ("receiver-SMTP ...
... whereby a server ("receiver-SMTP") may declare the maximum message
size it is willing to accept to a client ("sender-SMTP ...
... the name of the SMTP service extension is "Message Size
Declaration";
...
... optional parameter is allowed with this EHLO keyword value, a
decimal number indicating the fixed maximum message size in bytes
that the server will accept. The syntax of the parameter is as
follows, using the augmented BNF ...
... A parameter value of 0 (zero) indicates that no fixed maximum
message size is in force. If the parameter is omitted no
information is conveyed about the server's fixed maximum message
size;
...
... message size is in force. If the parameter is omitted no
information is conveyed about the server's fixed maximum message
size;
...
... The Message Size Declaration service extension ...
...
An SMTP server may have a fixed upper limit on message size. Any
attempt by a client to transfer a message which is larger than this
...
... the server (which discards the transferred message). If, however,
both client and server support the Message Size Declaration service
extension, such conditions may be detected before any transfer is
...
... EHLO command, and the response includes the EHLO keyword
value SIZE, then the Message Size Declaration extension is supported.
...
...
A server that supports the Message Size Declaration extension will
accept the extended version of the MAIL command ...
...
The fixed maximum message size is defined as the message size of the
largest message that a server is ever willing to accept. An attempt
...
...
The fixed maximum message size is defined as the message size of the
largest message that a server is ever willing to accept. An attempt
to transfer any message larger than the fixed maximum message size ...
... message size of the
largest message that a server is ever willing to accept. An attempt
to transfer any message larger than the fixed maximum message size
will always fail. The fixed maximum message size may be an
...
... to transfer any message larger than the fixed maximum message size
will always fail. The fixed maximum message size may be an
implementation artifact of the SMTP server, or it may be chosen by
...
... message size is defined as a client's estimate of the
message size for a particular message.
...
...
The value associated with the SIZE parameter is a decimal
representation of the declared message size in octets. This number
should include the message header, body, and the CR ...
...
Ideally, the declared message size is equal to the true message size.
However, since exact computation of the message size ...
...
Ideally, the declared message size is equal to the true message size.
However, since exact computation of the message size may be
...
... message size is equal to the true message size.
However, since exact computation of the message size may be
infeasable, the client may use a heuristically-derived estimate.
...
... client may use a heuristically-derived estimate.
Such heuristics should be chosen so that the declared message size is
usually larger than the actual message size. (This has the effect of
...
... heuristics should be chosen so that the declared message size is
usually larger than the actual message size. (This has the effect of
making the counting or non-counting of SMTP DATA dots largely an
...
... Upon receipt of an extended MAIL command containing a SIZE parameter,
a server should determine whether the declared message size exceeds
its fixed maximum message size. If the declared message size ...
... a server should determine whether the declared message size exceeds
its fixed maximum message size. If the declared message size is
smaller than the fixed maximum message size ...
... message size exceeds
its fixed maximum message size. If the declared message size is
smaller than the fixed maximum message size, the server may also wish
...
... message size. If the declared message size is
smaller than the fixed maximum message size, the server may also wish
to determine whether sufficient resources are available to buffer a
...
... to determine whether sufficient resources are available to buffer a
message of the declared message size and to maintain it in stable
storage, until the message can be delivered or relayed to each of its
recipients.
...
...
If the indicated size is larger than the server's fixed maximum
message size, the server responds with code "552 message size
exceeds fixed maximium message size ...
... If the indicated size is larger than the server's fixed maximum
message size, the server responds with code "552 message size
exceeds fixed maximium message size".
...
... message size, the server responds with code "552 message size
exceeds fixed maximium message size".
...
... If the code "552 message exceeds fixed maximum message size" is
received, the client should immediately send either a RSET command
...
... reply code
after the transfer phase of the DATA command, unless the actual size
of the message transferred is greater than the declared message size.
A server may also choose to accept a message which is somewhat larger
than the declared message size ...
... message size.
A server may also choose to accept a message which is somewhat larger
than the declared message size.
...
... Per-recipient rejection based on message size. ...
... client may use this extension to simply compare its
(perhaps estimated) size of the message that it wishes to relay, with
the server's fixed maximum message size (from the parameter to the
SIZE keyword in the EHLO response), to determine whether the server
...
... declare message sizes via the extended MAIL command. However,
neither will it be able to discover temporary limits on message size
due to server resource limitations, nor per-recipient limitations on
...
... due to server resource limitations, nor per-recipient limitations on
message size.
...
... largest message it will accept, or to inform the client that there is
no fixed limit on message size. Such a server must accept the
extended MAIL command and return a 552 reply code ...
... client's
declared size exceeds its fixed size limit (if any), but it need not
detect "temporary" limitations on message size.
...
... EHLO SIZE keyword is optional. If the
parameter is omitted entirely it indicates that the server does not
advertise a fixed maximum message size. A server that returns the
SIZE keyword with no parameter in response to the EHLO command may
...