30000 is a rather high number of messages to store in your inbox. It's advised to store your messages in multiple folders and to do your sorting on receipt of the messages with the filters in your sorting office.
However we are where se are and you want to export. Why do you want to export? What program needs access to your data or would it be sufficient to store your messages in multiple folders in TB's folder structure?
And what would be your sorting criterium? The from address or an address book group the sender belongs to. Or do you want to sort on the puchased product, is there any way to discover the purchased product?
Are there any other messages (as in not from customers) in your message base. Can those be recognozed easily. (Address book groups, mailing lists, whatever.)
But basically what you said was I want to sort my marbles without telling whether you want to sort on colour, size or material.
Basically I'd suggest you do your sorting in TB and then consider the need for exporting and the format you need your exports in.
You can do your sorting with TB's filters (manual or automatic), provided that you can define conditions for automatic sorting.
The exporting can be done with TB's export tool (if you want to export to some other message format) or with other filters. Tell us what you need.