Greetings! We have a Squid 3.1.10 (installed via yum on 64b CentOS6) that we are using as reverse proxy for Exchange. OWA, EWS, and RPC-over-HTTPS seem to be operating without incident, but we have run into "request too large" HTTP 413 errors with certain "large" ActiveSync POST messages from mobile phones. iPhone and Android, equal opportunity. To be correct, these large messages really aren't that large - we're talking kilobytes not mega. But they generate a 413 error and stay stuck in the phone's outbox. Other (smaller) messages sent after will sidestep the blockage and are sent thru. Our Exchange 2010 is dual Client Access Server DAG fronted by a hardware- based network load balancer. Squid points to the HLB, the HLB to the DAG, and ultimately to the active CAS. If we run the same tests internally (ie, injecting the message at the HLB) everything goes thru fine. This would seem to indicate that the source of the 413 is the proxy itself. But per the squid config (below) we should be running at "unlimited" request size, so I'm not sure why 413 would be thrown. The log snippet below should show a sync transaction from an iPhone followed by a failed "large" message send attempt. This is followed by a successful send of a smaller message - so we know a POST works - and again, a failed retry of the one that still remains queued. I tried to correlate to cache.log running as "-k debug" but it is difficult with all the traffic. Any ideas? --bill visible_hostname mail.verance.com via off redirect_rewrites_host_header off forwarded_for transparent ignore_expect_100 on ssl_unclean_shutdown on request_body_max_size 0 #client_request_buffer_max_size 5 MB maximum_object_size_in_memory 128 KB cache_mem 32 MB 1376678951.412 1259 IP.IP.IP.IP TCP_MISS/000 0 POST https://mail.verance.com/Microsoft-Server-ActiveSync? - FIRST_UP_PARENT/EXCH-Mail - 1376678951.562 169 IP.IP.IP.IP TCP_MISS/200 446 POST https://mail.verance.com/Microsoft-Server-ActiveSync? - FIRST_UP_PARENT/EXCH-Mail application/vnd.ms-sync.wbxml 1376679016.869 940 IP.IP.IP.IP TCP_MISS/413 349 POST https://mail.verance.com/Microsoft-Server-ActiveSync? - FIRST_UP_PARENT/EXCH-Mail text/html 1376679037.864 806 IP.IP.IP.IP TCP_MISS/200 184 POST https://mail.verance.com/Microsoft-Server-ActiveSync? - FIRST_UP_PARENT/EXCH-Mail - 1376679038.409 84897 IP.IP.IP.IP TCP_MISS/000 0 POST https://mail.verance.com/Microsoft-Server-ActiveSync? - FIRST_UP_PARENT/EXCH-Mail - 1376679038.623 214 IP.IP.IP.IP TCP_MISS/200 497 POST https://mail.verance.com/Microsoft-Server-ActiveSync? - FIRST_UP_PARENT/EXCH-Mail application/vnd.ms-sync.wbxml 1376679039.514 766 IP.IP.IP.IP TCP_MISS/413 349 POST https://mail.verance.com/Microsoft-Server-ActiveSync? - FIRST_UP_PARENT/EXCH-Mail text/html
