Can my travel agency software send my customer their trip details on WhatsApp instead of email?

Yes, in most setups it can, and many agencies now use it because a message on a phone gets read far faster than an email does. The trip details sit on the booking already, so the message goes out from that record with the traveller name, the dates and the reference filled in, and whatever your staff send is saved against the booking so everyone can see what the customer was told.

It works best for short, timely things. A confirmation after booking, a reminder the day before travel, a note that a flight time has moved, a nudge for a document you are waiting on. Longer paperwork such as a full itinerary or a voucher is usually better sent as a file or a link, because nobody wants to read several pages inside a chat window.

There are real limits here and they are not ours to remove. Messaging on WhatsApp runs through the messaging platform itself, so you need an approved business account, and the first message in a conversation has to follow one of their approved templates rather than free text. Customers also have to have agreed to be contacted that way. Whether this is switched on for you depends on your plan and on that approval coming through, and it can take a little time to get in place.

Decide which two or three messages you would actually want to go out automatically, then ask whoever looks after your system what is needed to get your business messaging account approved for them.