process-send-string (send via smtp) broken in 21.2.22, 23 and 24 under NT

Hi, About a week or so ago I posted a message about a problem I had with sending base64 encoded files containing more than 100-150 lines of text via smtp. I didn't get much response although the problem is very real and IMHO very serious (in my case it forces me to use 21.2.20). Hence I'm reporting it again, hoping for a reply from people maintaining that code. The problem appeared between 21.2.20 and 21.2.22 (I never tried 21.2.21). It stayed in 21.2.23, and I just checked that it is still present in 21.2.24. The problem is 100% reproducible on my system. I am sending a 115k .zip file as base64-encoded attachment. In 21.2.20 all works perfectly. In 21.2.22 and up, after an initial brief period of activity (which I see by my cable modem's lights) things freeze up. Pressing C-g quits the sending, and using the debug log of smtp session during my tests I saw that process-send-string (which is internal XEmacs function) stops sening lines after about 100-150 lines (the exact number varied from one try to another). It is definitely *not* caused by network problems - I did my tests many times, one after another, and in 100% of cases 21.2.20 succeeded while newer versions failed in exactly the same manner. My connection is a cable modem. OS is NT 4 sp5. Perhaps relevant is the fact that I have a *dual* PII 450mhz system (the bug feels like it could be caused by a race condition). It could even be an os bug, but the fact that both XEmacs 21.2.20 and MS Outlook Express work while 21.2.22 up fail make me think that that is not the case. Please, people who know/support/develop the relevant XEmacs code - take a look at this problem. If you can't reproduce it on your systems, I'm more than willing to do tests on mine - but the problem *is* real, and just hoping that it will go away is not the best way to handle it. Or perhaps I'm missing something obvious - enlighten me then. Thanks. I'm using native win32 build (by vc++ 6.0). -- Cheers, -Dima.