You can add attachments alongside your invoices or estimates when sending them by email or as e-invoices. To add an attachment, click on Choose file... in the email or e-invoice sending window. All major file types are supported (e.g. pdf, zip, jpg etc.) and the maximum size of all attached files that can be sent in a single email is 20MB. Please note, that this feature is a Premium Feature, and as such you need a Premium plan to use it.
When you use Zervant to send your document vs. your own email, the invoice or estimate is always automatically added as an attachment to the email.