Unavailable Servers
-------------------

   If a server seems to be unreachable, Gnus will mark that server as
`denied'.  That means that any subsequent attempt to make contact with
that server will just be ignored.  "It can't be opened," Gnus will tell
you, without making the least effort to see whether that is actually
the case or not.

   That might seem quite naughty, but it does make sense most of the
time.  Let's say you have 10 groups subscribed to the server
`nepholococcygia.com'.  This server is located somewhere quite far away
from you, the machine is quite, so it takes 1 minute just to find out
that it refuses connection from you today.  If Gnus were to attempt to
do that 10 times, you'd be quite annoyed, so Gnus won't attempt to do
that.  Once it has gotten a single "connection refused", it will regard
that server as "down".

   So, what happens if the machine was only feeling unwell temporarily?
How do you test to see whether the machine has come up again?

   You jump to the server buffer (see The Server Buffer.) and poke
it with the following commands:

`O'
     Try to establish connection to the server on the current line
     (`gnus-server-open-server').

`C'
     Close the connection (if any) to the server
     (`gnus-server-close-server').

`D'
     Mark the current server as unreachable (`gnus-server-deny-server').

`R'
     Remove all marks to whether Gnus was denied connection from all
     servers (`gnus-server-remove-denials').