Brian Denney writes:
[just the full copy of a long message, sixteen times]

Send mail to srfi-25xxxxxx@srfi.schemers.org with subject reading
unsubscribe.

Every message from the list contains this header line (I split it in
two lines; unsplit):
# List-Unsubscribe: <mailto:srfi-25xxxxxx@srfi.schemers.org?\
# subject=unsubscribe>

The short page <http://srfi.schemers.org/> shows a short list of
links, one of them clearly spelling
* SRFI Mailing Lists: Subscribing/Unsubscribing.

It points to <http://srfi.schemers.org/srfi-list-subscribe.html>. Go
there to see how to remove yourself from srfi-auto-subscribe, in case
being on that is the reason you were put on srfi-25.

As a last resort, when all else fails, ask the editors at
xxxxxx@srfi.schemers.org, politely.
--
Jussi