• Note about it being impossible to reliably specify the server settings, and instruct user to contact ISP's customer service etc.

<!DOCTYPE accounts [

<!-- root element -->
<!ELEMENT accounts (account*)>
<!ATTLIST accounts
          xmlns CDATA #FIXED "http://www.osafoundation.org/namespaces/accountsdb"
>

<!-- actual account(s) -->
<!ELEMENT account (email, server+)>

<!-- The part of the email address after the @-sign -->
<!ELEMENT email (#PCDATA)>

<!-- server(s) for the email address -->
<!ELEMENT server (machine, port?, secure-connection?, secure-authentication?)>
<!ATTLIST server
          type            (IMAP|POP|SMTP)   #REQUIRED
          preferred-order NUMBER            #IMPLIED
>

<!-- The name/address of the email server. If prefix specified, then username must be prefixed to machine
        name to get the actual name. -->
<!ELEMENT machine (#PCDATA)>
<!ATTLIST machine
          prefix (username) #IMPLIED
>
 
<!-- Port on the machine. If omitted, will be inferred from server type
     and secure-connection. -->
<!ELEMENT port EMPTY>
<!ATTLIST port
          number NUMBER #REQUIRED
>

<!-- Whether to use secure connection or not. Value could perhaps specify
     the type and version of the secure connection, for example "TLS 1.0".
     If omitted, will default to secure connection using SSL.
-->
<!ELEMENT secure-connection (#PCDATA)>

<!-- Whether to use secure authentication or not, and if so, maybe specify
     type of secure authentication as well.
     If omitted, will default to secure authentication.
-->
<!ELEMENT secure-authentication (#PCDATA)>

]>

<!-- Example -->
<accounts xmlns="http://www.osafoundation.org/namespaces/accountsdb">
  <account>
    <email>osafoundation.org</email>
    <server type="IMAP" preferred-order="1">
      <machine>mail.osafoundation.org</machine>
      <port number="993"/>
      <secure-connection>TLS</secure-connection>
      <secure-authentication>No<secure-authentication>
    </server>
    <server type="SMTP" preferred-order="1">
      <machine>mail.osafoundation.org</machine>
      <!-- port defaults to 25 -->
      <secure-connection>TLS</secure-connection>
      <secure-authentication>No<secure-authentication>
    </server>
  </account>
</accounts>