I got the email but there is no attachment.
The email always sends, even on the rare occasion the PDF could not be produced at that moment — telling you the rent settled matters more than the attachment. The document is still in Documents, and the "email me a copy" action there will send it again.
From the guide Receipts, Notices & Statements.
Receipts, Notices & Statements
When something happens that you should have a record of — rent settles, a deposit is taken, a notice is served, an application is decided — Seayora produces a PDF, emails it to you with the document attached, and keeps a copy in Documents. It is the same document in both places, and it stays in your account whether or not you keep the email.
Read the whole guide: Receipts, Notices & Statements