Mine

client.address_book.add_messenger_contact('foohotmail.com')

DEBUG:Service:>>> POST /abservice/abservice.asmx HTTP/1.0
Content-Length: 1904
Proxy-Connection: Keep-Alive
SOAPAction: http://www.msn.com/webservices/AddressBook/ABContactAdd
Host: contacts.msn.com:80
Accept: text/*
User-Agent: gnet/0.1 (Linux i686)
Connection: Keep-Alive
Cache-Control: no-cache
Content-Type: text/xml; charset=utf-8

<?xml version='1.0' encoding='utf-8'?><soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"><soap:Header><ABApplicationHeader xmlns="http://www.msn.com/webservices/AddressBook"><ApplicationId xmlns="http://www.msn.com/webservices/AddressBook">996CDE1E-AA53-4477-B943-2BE802EA6166</ApplicationId><IsMigration xmlns="http://www.msn.com/webservices/AddressBook">false</IsMigration><PartnerScenario xmlns="http://www.msn.com/webservices/AddressBook">ContactSave</PartnerScenario></ABApplicationHeader><ABAuthHeader xmlns="http://www.msn.com/webservices/AddressBook"><ManagedGroupRequest xmlns="http://www.msn.com/webservices/AddressBook">false</ManagedGroupRequest><TicketToken xmlns="http://www.msn.com/webservices/AddressBook">t=9KuBfzLg0Eqj7PqeaCcMTy2n*W*H6W3x0B5G4THkNtwF!dC4k9P60yczAsUi8yMKwzoF4mOwTGQtpQmjM0CcakflrJ2Wh9sSyUT2AHpXRmw5JxEWYPO*jiZTurhe0IiUCAa7Yd2*CbFUrq3AS4Nld8pA$$&amp;p=9lPaKTsq0F4Zg68dn7Au558r9s2bJvg*Xs2UnOWo4KNA2yeT5TCQRwlsofkzKKgbCXQP*VoUfUyn17Y8*QUrxn7Efw2MrBU!1buHpiEj4M3LjpzL4gemBMPkQE3lEMPHsGiv7N7p7MZbgIqfsjTP6SvBYXhC5Yq*3xInuGEr9FhBWJGTIEsjFa!Vxv3PV2fMjb</TicketToken></ABAuthHeader></soap:Header><soap:Body><ABContactAdd xmlns="http://www.msn.com/webservices/AddressBook"><abId>00000000-0000-0000-0000-000000000000</abId><contacts><Contact xmlns="http://www.msn.com/webservices/AddressBook"><contactInfo><passportName>foohotmail.com</passportName><isMessengerUser>true</isMessengerUser><contactType>Regular</contactType><MessengerMemberInfo><PendingAnnotations><Annotation><Name>MSN.IM.InviteMessage</Name><Value></Value></Annotation></PendingAnnotations><DisplayName></DisplayName></MessengerMemberInfo></contactInfo></Contact></contacts><options><EnableAllowListManagement>true</EnableAllowListManagement></options></ABContactAdd></soap:Body></soap:Envelope>
DEBUG:Service:<<< HTTP/1.1 500 Internal Server Error
Connection: keep-alive
Date: Wed, 20 Feb 2008 14:20:09 GMT
Server: Microsoft-IIS/6.0
P3P: CP="BUS CUR CONo FIN IVDo ONL OUR PHY SAMo TELo"
X-Powered-By: ASP.NET
X-MSNSERVER: BAYABCHWBB141
X-AspNet-Version: 2.0.50727
Cache-Control: private
Content-Type: text/xml; charset=utf-8
Content-Length: 946

<?xml version="1.0" encoding="utf-8"?><soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"><soap:Body><soap:Fault><faultcode>soap:Client</faultcode><faultstring>Malformed email Argument Email missing '@' character</faultstring><faultactor>http://www.msn.com/webservices/AddressBook/ABContactAdd</faultactor><detail><errorcode xmlns="http://www.msn.com/webservices/AddressBook">BadEmailArgument</errorcode><errorstring xmlns="http://www.msn.com/webservices/AddressBook">Malformed email Argument Email missing '@' character</errorstring><machineName xmlns="http://www.msn.com/webservices/AddressBook">BAYABCHWBB141</machineName><additionalDetails><originalExceptionErrorMessage>Malformed email Argument Email missing '@' character</originalExceptionErrorMessage></additionalDetails></detail></soap:Fault></soap:Body></soap:Envelope>
CRITICAL:Events:Client error: 3 --> 0