Can't send any mail

[David Abrahams <dave@boost-consulting.com>]

[-- Attachment #1: Type: text/plain, Size: 1199 bytes --]

After foolishly straying from Gnus for a while I am trying to return,
and I find myself unable to send any mail:

--- schnipp ---
Debugger entered--Lisp error: (file-error "make client process failed"
"software caused connection abort" :name "SMTP" :buffer #<buffer *trace
of SMTP session to smtp.rcn.com*> :host "smtp.rcn.com" :service 25)
  make-network-process(:name "SMTP" :buffer #<buffer *trace of SMTP
session to smtp.rcn.com*> :host "smtp.rcn.com" :service 25)
  open-network-stream("SMTP" #<buffer *trace of SMTP session to
smtp.rcn.com*> "smtp.rcn.com" 25)
  smtpmail-open-stream(#<buffer *trace of SMTP session to smtp.rcn.com*>
"smtp.rcn.com" 25)
  byte-code("ÆÇÈ\b\"!\x11r	q? ?Ê	\b\n#\x13\x1e
--- schnapp ---

I similarly am unable to telnet to that server:
--- schnipp ---
C:\src\emacs>telnet smtp.rcn.com 25
Connecting To smtp.rcn.com...Could not open connection to the host, on
port 25: Connect failed
--- schnapp ---

And when I try that, ethereal shows *no* packet traffic at all.

However, I can send from Thunderbird without problems.  The ethereal
trace is enclosed.  Any help would be massively appreciated!
Thanks,

-- 
Dave Abrahams
Boost Consulting
http://www.boost-consulting.com

[-- Attachment #2: packets.tar.gz --]
[-- Type: application/gzip, Size: 7565 bytes --]