Retrieving emails from a server to my iPad

Hi,

I've set up an iPad for a manager at work to use to receive their emails. The emails are stored on a third party server, and most of the time we use Outlook on our office PCs to retrieve the emails. The iPad is kept locked up in the office when not being used by the manager, within the range of a wi-fi network to which it usually connects. I was expecting it to be able to retrieve emails sent to the manager's address, but it only ever seems to retrieve emails that are sent while it is active.

I've made sure the IMAP and account settings are correct, and checked with our webspace provider that the ports required on the incoming and outgoing mail server settings are the correct ones. The iPad will receive test emails that I send while it's on and active, so the address is correct and is receiving emails properly, but it still won't retrieve emails sent at any other time, and it seems I have to manually fetch them - it won't push them from the server at all.

I have a feeling that the problem is to do with the iPad not staying connected to the wi-fi network while locked up in the office - is there any way to ensure that the iPad stays connected to the wi-fi permanently as long as it doesn't leave the network's range, and are there any other settings I can use to get emails to push from the server to the iPad?

Many thanks, and please ask if you need any clarification.