Symptom:
validation of e-mail addresses in case of scheduling a meeting via the ctx scheduling api. Fails when the email contains a "+" sign.
A perfectly valid e-mail address like "john.doe+test@company.org" throws the following error:

<env:Envelope xmlns:env="http://schemas.xmlsoap.org/soap/envelope/">
    <env:Header/>
    <env:Body>
       <env:Fault>
          <faultcode>env:Server</faultcode>
          <faultstring>Invalid scheduler. The scheduler must be a valid email address.</faultstring>
          <detail>
             <ns2:APISchedulingException xmlns:ns2="http://sched.api.ctc.txbu.cisco.com">
                <causeCode>SCHEDULER_EMAIL_NOT_VALID</causeCode>
               <erc>ERC_SCHEDULING_VALIDATION_EXCEPTION</erc>
               <message>Invalid scheduler. The scheduler must be a valid email address.</message>
            </ns2:APISchedulingException>
         </detail>
      </env:Fault>
  </env:Body>
</env:Envelope>

The relevant part of the request was:
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:sch="http://sched.api.ctc.txbu.cisco.com">
   <soapenv:Header/>
   <soapenv:Body>
      <sch:scheduleMeeting>
     ... <schedulerEmail>john.doe+test@company.org</schedulerEmail> ...
      </sch:scheduleMeeting>
   </soapenv:Body>
</soapenv:Envelope>



CTX does not allow "+" as a regex pattern for acceptable email addresses.
These are the ones currently used by CTX:
"^[_A-Za-z0-9-]+(\\.[_A-Za-z0-9-]+)*@[A-Za-z0-9-]+(\\.[A-Za-z0-9-]+)*"

Conditions:
All current CTX versions