If you'd like to add any additional text to the confirmation emails sent by Trellis, you'll want to first edit your fundraiser, then head into Thank You Message in the sidebar.
Once you're in the Thank You Message section, you'll see several fields like shown below:
The first field, Thank You Message allows you to add any extra text to show donors and purchasers on the thank you page after a successful checkout.
The second field Email Contact lets you change the contact for the fundraiser, which is shown in several of the emails sent out automatically by Trellis.
The third field Other Details for Ticket & Item Purchases allows you to add text to the confirmation email sent out for Ticket, Item, and Auction purchases.
The last field, Other Details for Donation Purchases let's you add text to the confirmation email sent out for only donation purchases.
These fields give you the flexibility to acknowledge donors and purchasers (giving you the ability to send relevant verbiage to your patrons, depending on if it was a donation or a ticket/item/auction item purchase).