exchangewebservices - EWS call using Managed API 2.2 never returns -

i'm using ews managed api v2.2 make ews calls. @ 1 of customers, have weird situation service calls, service call, never receives response.

we setting explicit timeout, surrounding service calls logging , using ews trace listening. listener show ewsrequest soap message, , that's it. logging shows "before service call" log entry not "after service call" entry.

i suspected throttling might behind , have temporarily removed ews throttling limits no effect , in case, expect error response if throttling kicking in.

this how service initialised:

public exchangewebservice(string username, string password, string emailaddress, string exchangeurl, string exchangeversion) {     exchangeversion exversion = (exchangeversion)enum.parse(typeof(exchangeversion), exchangeversion);     _exchangeservice = createexchangeservice(username, password, emailaddress, exchangeurl, exversion);     _exchangeservice.timeout = 30000;            }  private static exchangeservice createexchangeservice(string username, string password, string emailaddress,                                                               string exchangeurl, exchangeversion exchangeversion) {      integrationlogging _il = new integrationlogging(constants.loggingsourcename);      exchangeservice service = new exchangeservice(exchangeversion);             qualifiedusername qualifiedname = new qualifiedusername(username);     networkcredential credentials = new networkcredential(qualifiedname.username, password);      if (qualifiedname.hasdomain)     {         credentials.domain = qualifiedname.domain;     }      service.credentials = credentials;      if (string.isnullorempty(exchangeurl))     {         if (string.isnullorempty(emailaddress))         {             throw new argumentexception("emailaddress , exchangeurl parameters cannot both empty");         }         else         {             _il.writetrace(string.format("createexchangeservice using auto discovery email address {0} , user name {1}. {2}", emailaddress, username, environment.stacktrace));             service.autodiscoverurl(emailaddress);         }     }     else     {         _il.writetrace(string.format("createexchangeservice using ews uri {0} , user name {1}", exchangeurl, username));         service.url = new uri(exchangeurl);     }      return service; } 

from 1 of methods never returns, first log entry not second , our perf monitor shows thread still running @ line of service call.

_il.writetrace("convertinternalidtoewsid:mailboxaddress=" + mailboxaddress);  alternateidbase _altbase = _exchangeservice.convertid(_alternateid, idformat.ewsid);  _il.writetrace("convertinternalidtoewsid:returned call");  return ((alternateid)_altbase).uniqueid; 

the service instance of type microsoft.exchange.webservices.data.exchangeservice.

this problem seems intermittent. how can call not result in response, exception or timeout?

hey i'll double check when i'm @ office... had similar issue...

in case return, had leave quite sometime.

i had mine wrapped in try/catch, , put break point on catch.

cannot remember, think happened when using wrong auto discover email address.

try {     service.autodiscoverurl(emailaddress); } catch (exception)  {  //break point here , leave @ least 10 min     throw; }