A request to subscribe to another's presence information is performed using an XMPP presence stanza. An example of such a stanza is:

<presence from="jane@example.com" to="john@example.org" type="subscribe"><status>This is a custom status</status><nick xmlns="http://jabber.org/protocol/nick">Jane</nick></presence>

The subscription stanza is typically received as it was sent. However, when the stanza is sent to an entity that's offline, the recipient will receive (when they are back online) a stanza that misses a lot of information, eg:

<presence from="jane@example.com" to="john@example.org" type="subscribe"/>

It appears that when the subscription request is stored for later delivery, details are lost. This is undesireable.