Trying to send an invoice to a supplier and quickbooks wont let me. Is it possible to do so?

Thanks for checking in with us, f12ryan.

The option to send an invoice to your supplier is unavailable in QuickBooks Online (QBO). However, you can save the invoice as a PDF file and email them to your supplier.

Here's how:

1. Go to Sales on the left side menu.
2. Choose Invoices and open the transaction you'll want to send.
3. Tick the Save and send button.
4. Tap Print.
5. Press the Printer icon.
6. Select the PDF driver to save the transaction in the Destination field. 
7. Click Print to upload the invoice.

Once done, open your email and send the invoice (as an attached file) to your supplier.

For more details about creating and sending invoices, check out this article: Create invoices in QuickBooks Online.

I've got a link here that provides you with articles about managing customer transactions: https://quickbooks.intuit.com/learn-support/manage-customers-and-income/misc/02/uk-manage-customers-and-income?label=QuickBooks%20Online.

Keep me posted if you need a hand with creating recurring transactions or any QBO related. I'm glad to help. Have a great day ahead.