MIME Content-type: and Content-disposition: header line parameter RFC 2231 encoding (parameterformatdefault, parameterformatminimizeencoded, parameterformatstripencoded)

MIME Content-type: and Content-disposition: header line parameter RFC 2231 encoding
As of Messaging Server 7.2-0.01,  the MTA supports RFC 2231 (MIME Parameter Value and Encoded Word Extensions), thus supporting use  of alternate character sets and languages in MIME parameters, as well  as supporting the segmentation of "long" parameter values.

As a separate issue from the truncation of very long parameter values as controlled by   and  ,  note that as of  Messaging Server 7.2-0.01 when RFC 2231 support  was added, the MTA will automatically segment long parameter values  according to RFC 2231 rules. (Note that the length at which RFC 2231 segmentation is triggered is not configurable.)  For  Messaging Server 7.2-0.01, parameter  values over 65 characters in length will automatically be segmented  into 40 character segments; e.g., filename="veryveryveryveryveryveryveryveryveryveryveryveryveryveryverylong.name" would become filename&#x2a;0="veryveryveryveryveryveryveryveryveryvery"; filename&#x2a;1="veryveryveryveryverylong.name" As of Messaging Server 7.4-0.01 and the implementation of  CR # 6924445, the length limit  for triggering parameter segmentation was increased from the prior 65  characters up to 70 characters. (In particular, as RFC 2046 limits the length of MIME boundary delimiters to at most 70 characters, this larger trigger length avoids triggering MIME parameter segmentation of compliant  boundary delimiters.)

New in 7.0.5 are the channel options,   , and   , with these last two options  providing new features to aide with cases of dealing with other  software that does not yet support RFC 2231. is the default and means to do normal RFC 2231 encoding, as needed. tells the MTA to attempt to remove any unnecessary or redundant RFC 2231 encoding from MIME  parameters including removing any RFC 2231 segmentation of parameters;  when it is applied, parameter segmentation will be removed and those  encoded words not involving charset or language information or 8 bit  characters will be replaced with regular parameter values. tells the MTA to strip any characters that would require RFC 2231 encoding from MIME parameters,  thereby allowing the parameter to be represented without any RFC 2231  encoding or segmentation.

For webmail (MSHTTP) generation of RFC 2231 encoded format, see the  MSHTTP option.

See also:
 * nameparameterlengthlimit Option
 * Attachments and MIME processing channel options
 * Channel options
 * rfc2231compliant Option