At 01:49 PM 1/24/97 -0500, you wrote:
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>The user name has been changed - the computer system has not.

No, the user name has NOT changed (the johndoe).

Actually the computer system HAS changed, as netcom has many identical
computers and which one you connect to is probably assigned randomly or by
load.  Netcom SHOULD use ix.netcom.com for all return addresses.  It is
somebody's problem, but not yours.

>I gave him a standard answer that the listserv software doesn't
>recognize these three addresses as related, but felt foolish doing so.
>I haven't received a response from him yet, but if I got such an
>explanation, my reaction would be "why not?"

Because that is the way it works.

>If both "johndoe" and the "ix.netcom.com" are identical in all three
>addresses, is there any situation in which they might be different people?

Yes.   Maybe not at netcom, but with many other places.

It is the way the net is, and you'll just have to accept it, as will your
user.  Have him talk to netcom tech support, because it just isn't your
problem.

dan