I released a preview version of ndsmail today. In the beginning it was not working at all on any nds other than mine, but I fixed it. Turned out the problem was in the ARM7 core. The FIFO buffers where not set up properly. Tomorrow I will try to find out why it crashes for some people at "Retrieving message headers" or "Closing connection".
If you want to send me a mail to my NDS: ndstest@NOSPAMPLEASEbronto-online.de. Of course you remove the NOSPAMPLEASE part first :)
SMTP is not implemented tho, so I won't be able to reply.