I did not have LimitRequestBody set in my apache configuration file or 
php.ini file. I tried setting it in the apache2 conf to a very high 
number, but still recieved the same problem, not when sending 
attachments, but simply when trying to reply to an email using 
Internet Explorer.



If the user right clicks on the new window and clicks "refresh" the 
page loads and the email can be sent, or if the user turns off  the 
"Compose in new window" option. This only seems to affect IE.



I am using Gentoo Linux with the following versions of Horde packages 
installed:



horde-3.0.5

horde-accounts-2.1.2

horde-forwards-2.2.2

horde-imp-4.0.3

horde-kronolith-2.0.3

horde-mnemo-2.0.1

horde-passwd-2.2.2

horde-pear-1.3-r3

horde-sork-0

horde-turba-2.0.3

horde-vacation-2.2.2

No feedback.

I was just having the same problem, and it turned out on RHEL, 
LimitRequestBody was set to 512k.  Check (and increase if necessary) 
your web server configuration for LimitRequestBody.



Also check your logs for something like:  Requested content-length of 
967055 is larger than the configured limit of 524288,



On IE when I encountered this problem, what I was getting was IE's 
generic "this page cannot be displayed" bs error.



If that's not set/happening, then the error is something different, 
but it looked a lot like what I was getting.

*Which* error page? What does it say? Is there anything in the log 
files, in the javascript console? You need to provide far more 
information.

I've had complaints from some of the employees that use webmail in my office.



If they open a compose popup window and then try to attach a file, 
when they go to click the attach button, in IE they get an error page. 
If I hit the backspace key and hit "Attach" a second time, it works 
fine. It also works if I turn off composing in a new popup window.



I suspect it might be a javascript issue.