nnimap:$server unavailable... Go offline?

[Chris Shenton <chris@shenton.org>]

gnus-version's value is "Gnus v5.10.3"

I have an nnimap server, connect to it (with starttls), read mail for
a while, then ignore it a while.  When I return, and do a "g" to check
mail (or go into a group to check headers, or...) Gnus reports

  Unable to open nnimap:myservername, go offline?

I see this is done in gnus-int.el: gnus-open-server, but don't
understand why it's happening.  Does it indicate that my IMAP server
has torn down the connection , but Gnus doesn't automatically
reconnect?

If I say "y", then Quit Gnus, then restart Gnus, it authenticates
again and all is well.

If I say "n", I don't know what state this is supposed to put me in,
but at times it's seemd unusable: I'm not Offline, but neither am I
Online; I can't exit *Summary* buffers cuz it can't write updates to
the server, I can't quit Gnus because I've got unsaved *Summary*s.
I'm in Limbo.

If my server (courier-imap-2.2.1, running without authdaemon stuff) is
tearing down the connection too early (maybe it thinks Gnus is idle?)
perhaps I can increase the timeout.  If I should be using IMAP from
Gnus in some other way (an Agent, whatever that is), I'd appreciate a
pointer.

Here's how I'm using it, splitting logic removed.  Thanks.


(setq
 gnus-secondary-select-methods
 '(
   (nnml "")
   (nnimap "pectopah"		      ;use ~/.authinfo for user/passwd
	   (nnimap-address "pectopah.shenton.org")
	   )
   )
  )