How about changing your settings in Offline Messages in Server settings in Wildfire Admin console.
Try to change the settings to Store Then Always Store and assign a bigger size for the offline messages.
This is my Settings:
XMPP provides the option for servers to store-and-forward IM messages when they are sent to a user that is not logged in. Supporting store-and-forward of ‘‘offline messages’’ can be a very convenient feature of an XMPP deployment. However, offline messages, like email, can take up a significant amount of space on a server. There are several options for handling offline messages; select the policy that best suites your needs.
Current size of all offline message: 0.02 MB
Offline Message Policy Bounce - Never store offline messages and bounce messages back to the sender.
Drop - Never store offline messages and drop messages so the sender is not notified.
Store - Store offline messages for later retrieval. Messages will be delivered the next time the recipient logs in. Choose a storage policy and storage store max size below.
Always Store - Always store messages,even if the max storage
Hope This helps.
Message was edited by: isiahjericho