There are multiple reasons why an invoice has not been sent/received,
Firstly, it could be that invoices are not set to send automatically after job completion, you can check this option in settings as shown below:
If you set your default notification method this will update for any new customers you add, however if you have any pre-existing customers you will need to update them manually, we can update these in bulk our side if needed.
In addition to this, if you haven't received an alert that there was a problem in sending the invoice, the invoice may have simply been directed to a customers spam mail folder, this can happen due to the customers personal privacy settings or even their internet provider, its always worth telling the customer to check their spam filters if they haven't seen your sent invoice.
If you have any more questions or queries, or would like to see what other features Squeegee has to offer, please take a look at our help page at https://squeeg.ee/help or alternatively you can ring us on, 020 7861 4401