We often OCR-convert address registers that include email addresses, and frequently also lists containing only email addresses. After capture, every email address is checked through a service that simulates sending to the addresses. Any addresses that prove not to work are then checked especially carefully for OCR errors directly against an image of the scanned email address!
In the delivery you receive an Excel file with a column of email addresses, plus columns for page number and line number, together with a PDF file for reference.