I am getting frequent "Error code: -3253 - Communication to server failed or was dropped" in Outlook for Mac 2011 (v. 14.5.4 on OS X Yosemite 10.10.5). I do not get this problem when I manually send and receive, only when the program automatically sends & receives (which is set to every 10 minutes). I've had this problem intermittently, but it has been particularly acute the past couple of weeks.