On Thu, Sep 22 2011, Katsumi Yamaoka wrote:

> Katsumi Yamaoka wrote: >> I realized what we have to fix is `mml-compute-boundary-1'. [...] >> The function looks for ones that are the same as a MIME boundary >> (e.g., =-=-=) in contents of MIME parts, and updates the boundary >> pattern so as to be unique, if any. Contents to be checked should >> be encoded ones, however it doesn't so. As for a file to attach, >> it reads the file without binding `coding-system-for-read', doesn't >> encode it, and looks for things like the boundary in it. That is >> the root cause of an XEmacs 21.5 error. > > Done. Not yet tested with XEmacs 21.5 though. > The new function definition encodes every part in the same way > practicing when actually sending them in advance and then looks > for things like a MIME boundary. So it may slow message sending. > In addition, it assumes that signing and encrypting will never > generate a boundary pattern in data.

Note that Aidan Kehoe added ".pdf" to `binary-file-regexps' in XEmacs 21.5 now[1].

If the slowdown is notable and the change is only because of the reported XEmacs problem, it is not necessary, I think. Or does your commit fix a more general problem?

[1] http://thread.gmane.org/gmane.emacs.xemacs.beta/35574