Can't reproduce in HEAD.

Pretty sure it was fixed by:

commit 8a62cd3d3d06261455110a17cec1f0eae1bd3cbc
Author: Michael M Slusarz <slusarz@horde.org>
Date:   Tue Feb 4 16:48:32 2014 -0700

     Fix fallback authentication handling errors

     Previously, it was relying on notification push apps to cause the fatal
     error. This was fortunate, but not the correct behavior.

I am almost certain that the URL in the browser remains as it were 
when the user left the application/browser as it was the last time 
they visited it.  In that case, the URL looks like this:

https://webmail.your.domain/imp/smartmobile.php#mailbox?mbox=SU5CT1g

In fact, if you just stay on the inbox view, when the refresh time 
interval has been reached, you see the spinning circle, the new mail 
arrives if any, inbox view is refreshed but the URL in the browser 
remains the same.

This may be a browser bug because it seems to always happen when the 
IMP session time has expired.  Although, very infrequently it may 
happen before then.

I wouldn't spend much time on this issue unless it is obviously a problem.

Thanks.

I meant the URL as seen in the browser.  I'm almost certain there is 
anchor (i.e. #) information in there, and that may be causing the 
issue.  Anchors won't appear in server logs since they are not sent to 
the server.

Ok, so once the smartphone client has passed the configured session 
expiration time, I open the browser where IMP is currently running, 
this triggers an automatic refresh for mail since the page that was 
open was the Inbox view.

I see the spinning circle for a few seconds and then the circle goes 
away leaving the previously displayed screen and the mail from the 
last refresh.

During the above, the following request is received by Apache:

webmail.your.domain 111.222.333.444 - username [17/Apr/2014:18:03:08 
-0400] "POST /services/ajax.php/imp/viewPort HTTP/1.1" 200 3431 
"https://webmail.your.domain/imp/smartmobile.php" "Mozilla/5.0 (Linux; 
U; Android 4.1.2; en-us; SGH-T989 Build/JZO54K) AppleWebKit/534.30 
(KHTML, like Gecko) Version/4.0 Mobile Safari/534.30"

Now I hit the "Folders' button where I get a screen with the top and 
bottom but no folders shown.  Then I hit the 'Applications' button and 
at this point, I get the Login screen with the popup box that says my 
session has expired.

Here are the requests for those:

webmail.your.domain 111.222.333.444 - username [17/Apr/2014:18:10:51 
-0400] "POST /services/ajax.php/imp/viewPort HTTP/1.1" 200 3431 
"https://webmail.your.domain/imp/smartmobile.php" "Mozilla/5.0 (Linux; 
U; Android 4.1.2; en-us; SGH-T989 Build/JZO54K) AppleWebKit/534.30 
(KHTML, like Gecko) Version/4.0 Mobile Safari/534.30"
webmail.your.domain 111.222.333.444 - username [17/Apr/2014:18:11:01 
-0400] "POST /services/ajax.php/imp/smartmobileFolderTree HTTP/1.1" 
200 3431 "https://webmail.your.domain/imp/smartmobile.php" 
"Mozilla/5.0 (Linux; U; Android 4.1.2; en-us; SGH-T989 Build/JZO54K) 
AppleWebKit/534.30 (KHTML, like Gecko) Version/4.0 Mobile Safari/534.30"
webmail.your.domain 111.222.333.444 - username [17/Apr/2014:18:11:11 
-0400] "POST /services/ajax.php/imp/smartmobileFolderTree HTTP/1.1" 
200 3431 "https://webmail.your.domain/imp/smartmobile.php" 
"Mozilla/5.0 (Linux; U; Android 4.1.2; en-us; SGH-T989 Build/JZO54K) 
AppleWebKit/534.30 (KHTML, like Gecko) Version/4.0 Mobile Safari/534.30"
webmail.your.domain 111.222.333.444 - - [17/Apr/2014:18:11:14 -0400] 
"GET /services/portal/smartmobile.php HTTP/1.1" 401 1280 
"https://webmail.your.domain/imp/smartmobile.php" "Mozilla/5.0 (Linux; 
U; Android 4.1.2; en-us; SGH-T989 Build/JZO54K) AppleWebKit/534.30 
(KHTML, like Gecko) Version/4.0 Mobile Safari/534.30"
webmail.your.domain 111.222.333.444 - username [17/Apr/2014:18:11:14 
-0400] "GET /services/portal/smartmobile.php HTTP/1.1" 302 - 
"https://webmail.your.domain/imp/smartmobile.php" "Mozilla/5.0 (Linux; 
U; Android 4.1.2; en-us; SGH-T989 Build/JZO54K) AppleWebKit/534.30 
(KHTML, like Gecko) Version/4.0 Mobile Safari/534.30"
webmail.your.domain 111.222.333.444 - - [17/Apr/2014:18:11:15 -0400] 
"GET 
/login.php?url=https%3A%2F%2Fwebmail.your.domain%2Fservices%2Fportal%2Fsmartmobile.php&horde_logout_token=hv2BW_aJ-xTZoAacYSQ3Uw1&app=horde&logout_reason=102 HTTP/1.1" 401 1258 "https://webmail.your.domain/imp/smartmobile.php" "Mozilla/5.0 (Linux; U; Android 4.1.2; en-us; SGH-T989 Build/JZO54K) AppleWebKit/534.30 (KHTML, like Gecko) Version/4.0 Mobile 
Safari/534.30"
webmail.your.domain 111.222.333.444 - username [17/Apr/2014:18:11:15 
-0400] "GET 
/login.php?url=https%3A%2F%2Fwebmail.your.domain%2Fservices%2Fportal%2Fsmartmobile.php&horde_logout_token=hv2BW_aJ-xTZoAacYSQ3Uw1&app=horde&logout_reason=102 HTTP/1.1" 200 6071 "https://webmail.your.domain/imp/smartmobile.php" "Mozilla/5.0 (Linux; U; Android 4.1.2; en-us; SGH-T989 Build/JZO54K) AppleWebKit/534.30 (KHTML, like Gecko) Version/4.0 Mobile 
Safari/534.30"
webmail.your.domain 111.222.333.444 - username [17/Apr/2014:18:11:15 
-0400] "GET /static/4eb2cf6edb0cf1289bd1aadcad381b35.css HTTP/1.1" 200 
124332 
"https://webmail.your.domain/login.php?url=https%3A%2F%2Fwebmail.your.domain%2Fservices%2Fportal%2Fsmartmobile.php&horde_logout_token=hv2BW_aJ-xTZoAacYSQ3Uw1&app=horde&logout_reason=102" "Mozilla/5.0 (Linux; U; Android 4.1.2; en-us; SGH-T989 Build/JZO54K) AppleWebKit/534.30 (KHTML, like Gecko) Version/4.0 Mobile 
Safari/534.30"
webmail.your.domain 111.222.333.444 - username [17/Apr/2014:18:11:15 
-0400] "GET /static/83d98e518eb43824e2e6da429a8874648c4e8edf.js 
HTTP/1.1" 200 108552 
"https://webmail.your.domain/login.php?url=https%3A%2F%2Fwebmail.your.domain%2Fservices%2Fportal%2Fsmartmobile.php&horde_logout_token=hv2BW_aJ-xTZoAacYSQ3Uw1&app=horde&logout_reason=102" "Mozilla/5.0 (Linux; U; Android 4.1.2; en-us; SGH-T989 Build/JZO54K) AppleWebKit/534.30 (KHTML, like Gecko) Version/4.0 Mobile 
Safari/534.30"
webmail.your.domain 111.222.333.444 - username [17/Apr/2014:18:11:15 
-0400] "GET /static/48c05850fe64dd6aa5e60aa50c8f8b3e2f027eb0.js 
HTTP/1.1" 200 145397 
"https://webmail.your.domain/login.php?url=https%3A%2F%2Fwebmail.your.domain%2Fservices%2Fportal%2Fsmartmobile.php&horde_logout_token=hv2BW_aJ-xTZoAacYSQ3Uw1&app=horde&logout_reason=102" "Mozilla/5.0 (Linux; U; Android 4.1.2; en-us; SGH-T989 Build/JZO54K) AppleWebKit/534.30 (KHTML, like Gecko) Version/4.0 Mobile 
Safari/534.30"

What does the URL look like when this happens?

At some point after IMP 6.1.6, when a session expires for a 
mobile/smartphone mail client, the client does not properly get 
redirected to the login page or see the usual temporary message that 
informs them of the expired session.

Instead, the client only sees the spinning circle or is able to 
navigate from Inbox view to folder view and back, only seeing the same 
set of messages from before the session expiration time.

In previous releases, the client was clearly informed of the expired 
session and (I think) was redirected automatically to the login page 
(which I think should be the expected behavior).  Now, they are not 
and have to manually logoff or select the login bookmark from the 
browser menu and more often the session expired message is not 
displayed.

Thanks