Send email using special characters using Exchange Web Services

Question

When you try to send an email using the Managed Exchange Web Services API in Exchange Server 2010 Service Pack 1, a ServiceException is thrown with ErrorCode ErrorInvalidRecipients when the recipient's email address (of @ at the left) contains Danish letters æøå in this case.

Are these characters simply illegal in the local part of the email addresses, or should I somehow encode the address?

Update: Here is the source code and trace data:

var service = new ExchangeService(ExchangeVersion.Exchange2010_SP1);
service.AutodiscoverUrl("[e-mail]");
EmailMessage email = new EmailMessage(service);
email.Body = "Test";
email.Subject = "Test";
email.ToRecipients.Add("æøå@domain.com");
email.Send();

Trace data from EWS shows the following:

Request Headers:

POST /EWS/Exchange.asmx HTTP/1.1
Content-Type: text/xml; charset=utf-8
Accept: text/xml
User-Agent: ExchangeServicesClient/14.03.0032.000
Accept-Encoding: gzip,deflate

Inquiry:

<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
  <soap:Header>
    <t:RequestServerVersion Version="Exchange2010_SP1" />
  </soap:Header>
  <soap:Body>
    <m:CreateItem MessageDisposition="SendOnly">
      <m:Items>
        <t:Message>
          <t:Subject>Test</t:Subject>
          <t:Body BodyType="HTML">Test</t:Body>
          <t:ToRecipients>
            <t:Mailbox>
              <t:EmailAddress>æøå@domain.com</t:EmailAddress>
            </t:Mailbox>
          </t:ToRecipients>
        </t:Message>
      </m:Items>
    </m:CreateItem>
  </soap:Body>
</soap:Envelope>

Answer:

<?xml version="1.0" encoding="utf-8"?>
<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/">
  <s:Header>
    <h:ServerVersionInfo MajorVersion="14" MinorVersion="1" MajorBuildNumber="438" MinorBuildNumber="0" Version="Exchange2010_SP1" xmlns:h="http://schemas.microsoft.com/exchange/services/2006/types" xmlns="http://schemas.microsoft.com/exchange/services/2006/types" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" />
  </s:Header>
  <s:Body xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
    <m:CreateItemResponse xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types">
      <m:ResponseMessages>
        <m:CreateItemResponseMessage ResponseClass="Error">
          <m:MessageText>One or more recipients are invalid.</m:MessageText>
          <m:ResponseCode>ErrorInvalidRecipients</m:ResponseCode>
          <m:DescriptiveLinkKey>0</m:DescriptiveLinkKey>
          <m:Items />
        </m:CreateItemResponseMessage>
      </m:ResponseMessages>
    </m:CreateItemResponse>
  </s:Body>
</s:Envelope>

---

, Outlook :

Answer 1

, Exchange, , :

- , (=) (-) . : (/) (_). US-ASCII (+) ASCII . , +20.

http://technet.microsoft.com/en-us/library/bb430743 (v = exchangeg.141).aspx

, "æøå@domain.com" "[e-mail]"

EDIT:

"" , .

GetExchangeEncodedRecipient, RFC 5321 RFC 3461.

    public static string GetExchangeEncodedRecipient(string recipient) {
        int atIdx = recipient.LastIndexOf('@');

        if (atIdx < 0) {
            throw new ArgumentException("Unable to parse domain portion of \"recipient\" email address.");
        }

        string namepart = recipient.Substring(0, atIdx);
        string domainPart = recipient.Substring(atIdx + 1);
        //need to encode any special characters in the domain name
        System.Globalization.IdnMapping punycode = new System.Globalization.IdnMapping();
        domainPart = "@" + punycode.GetAscii(domainPart);

        return String.Concat(namepart.Select(c => GetExchangeEncodedChar(c))) + domainPart;
    }
    private static string GetExchangeEncodedChar(char c) {
        string encodedChar = c.ToString();
        int charASCIICode = (int)c;
        //Encode according to RFC5321, https://tools.ietf.org/html/rfc5321#section-4.1.2
        //  which references rfc3461 "xtext" format. https://tools.ietf.org/html/rfc3461#section-4 
        if(charASCIICode >= 33 && charASCIICode <= 126 && c != '+' && c != '=')
        {
            //This is a character in the valid 33-126 ASCII range for email addresses, which does not need encoded.
            return c.ToString();
        }
        else if(c == '/'){
            //A forward slash (/) is replaced by an underscore (_).
            return "_";
        }
        else { 
            return "+" + ((int)c).ToString("x2").ToUpper();
        }
    }

GetExchangeEncodedRecipient . :

string recipient = @"user1æøå@dømain.com";
string encodedAddress = GetExchangeEncodedRecipient(recipient);
Console.WriteLine("Original: {0}, Encoded: {1}", recipient, encodedAddress);

, :

: user1æøå@dømain.com, Encoded: [e-mail]

"" , "" ASCII, .

: [e-mail], : [e-mail]