Can a company's employees book their own trips on my portal instead of emailing my office every time?

Yes, and for most corporate accounts this is the main reason they move to a portal in the first place. You give the company its own login area where each employee sees the same flights, hotels and transfers you would quote them, already filtered to what their company allows. They pick what they need and confirm it themselves, and your team only steps in when something needs a human, such as an unusual route or a change after ticketing.

What the employee sees is not the open public site. Their profile carries their name, passport details and cost centre, so those fields fill in on their own and there is far less chance of a spelling mistake. The company can also decide that certain trips still need a sign off before the booking goes through, in which case the employee books as normal and the request waits quietly until the named approver clears it.

Be honest with the client about where this stops. Self booking works well for straightforward point to point trips, but complicated multi leg journeys, group travel and anything involving a special fare are usually better handled by your staff, because the supplier will not always price those correctly on an automated screen. How much of this you get also depends on your plan and on which suppliers you have connected.

The sensible way to start is to let one department book their own simple trips for a month while your team keeps handling the rest, then widen it once the company sees the bookings coming through clean.