CODEWITHSUNDEEP
c#.netactive-directoryexchangewebservices
bernhof
bernhof

Reputation: 6320

Determine if mailbox exists using Exchange Web Services API

Using the Exchange Web Services API, is it possible to determine whether a mailbox/e-mail address such as [email protected] exists within an organization?

If so, which is the simplest way to do this and is it possible without the use of impersonation?

Case: A Windows Service regularly sends e-mails to people within the organization. It does not have any explicit knowledge about their e-mail adresses. It only knows their username and assumes that their e-mail address is username@mydomain.com. This is true for all users except for a few that do not have mailboxes. In these cases, it should not attempt to send the e-mail in the first place.

Solution:

As suggested by mathieu: look for user and e-mail address in Active Directory instead. This function gets the job done:

using System.DirectoryServices.AccountManagement;
// ...

public static bool TryGetUserEmailAddress(string userName, out string email)
{
  using (PrincipalContext domainContext = 
    new PrincipalContext(ContextType.Domain, Environment.UserDomainName))
  using (UserPrincipal user = 
    UserPrincipal.FindByIdentity(domainContext, userName))
  {
    if (user != null && !string.IsNullOrWhiteSpace(user.EmailAddress))
    {
      email = user.EmailAddress;
      return true;
    }
  }
  email = null;
  return false; // user not found or no e-mail address specified
}

Upvotes: 2

Views: 5109

Answers (2)

Mohanad Haddadin
Mohanad Haddadin

Reputation: 589

there is an easy way to do it by checking the user availability like the following code. I tried this and it is working for me.

I am not sure about other cases when availability result returns error but for sure when the email is not right it does

to define your exchange service refer to this: https://learn.microsoft.com/en-us/exchange/client-developer/exchange-web-services/get-started-with-ews-managed-api-client-applications

ExchangeService service = new ExchangeService(ExchangeVersion.Exchange2007_SP1);//You version
service.Credentials = new WebCredentials("[email protected]", "password");
service.AutodiscoverUrl("[email protected]", RedirectionUrlValidationCallback);
string email = "[email protected]";

// Get User Availability after 6 months 
AttendeeInfo attendee = new AttendeeInfo(email);
var attnds = new List<AttendeeInfo>();
attnds.Add(attendee);
var freeTime = service.GetUserAvailability(attnds, new 
TimeWindow(DateTime.Now.AddMonths(6), DateTime.Now.AddMonths(6).AddDays(1)), AvailabilityData.FreeBusyAndSuggestions);
//if you receive result with error then there is a big possibility that the email is not right
if(freetimes.AttendeesAvailability.OverallResult == ServiceResult.Error)
{
     return false;
}
return true;

Upvotes: 0

mathieu
mathieu

Reputation: 31202

Determining if an user has a mailbox with EWS only could be more complicated than expected, especially without impersonation.

If you're in an Active Directory domain, you should rely on the DirectoryEntry information to determine the mailbox of an user, and send email accordingly. If you got your user login, it's really easy to get the associated DirectoryEntry.

Upvotes: 1

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