Question XML API response not returning all nodes

[Obakemono]

Hello,

I'm developing my first extension for plesk and i'm using the XML API on Plesk Onyx 17.5.3

I need to get the current outgoing mail limit for a given email account, but the response to my request doesn't include the outgoing-messages-mbox-limit node under the mailname node, the option is set on the account and i don't have any trouble retrieving the same info for a subscription for example.

This is the structure of my request:

              $getSubscriptionOutMailLimit = <<<APICALL
              <webspace>
                <get>
                  <filter>
                    <name>$siteName</name>
                  </filter>
                  <dataset>
                    <mail/>
                  </dataset>
                </get>
              </webspace>
APICALL;

And the result is:

Information: SimpleXMLElement Object
(
[@attributes] => Array
(
[version] => 1.6.9.0
)

[mail] => SimpleXMLElement Object
(
[get_info] => SimpleXMLElement Object
(
[result] => SimpleXMLElement Object
(
[status] => ok
[mailname] => SimpleXMLElement Object
(
[id] => 1
[name] => wesley
[user-guid] => d328cfe1-5efd-4139-a4fa-ffcc984602c9
[antivir] => off
[description] => wesley crusher
)

)

)

)

)

According to documentation, the outgoing-messages-mbox-limit node is optional under the mailname node.

I have the outgoing limit options activated inside plesk and the field is set.

¿Am i doing anything wrong? ¿Why is not that node being returned? ¿Is there a way to force the response to return every node?

Any hint would be apreciated.

Thank you!