If your customers are letting you know they aren't receiving system emails (statements, invoices, proposals, order confirmations, etc.), or you aren't receiving web order notifications, there could be a problem with your email provider.
First, it's important to determine what sending email address you are using. AOL, Yahoo and vanity emails are known for getting successfully sent emails flagged/rejected by the recipient's email. This can generally be avoided by implementing a Gmail forwarding address in the Sending Email field.
Create a New Gmail Account
You will need to insert a Gmail address into the Sending Email field. Create a new Gmail account by going to Gmail.com and registering.
Important note: If you have an existing Gmail address, you are more than welcome to use that instead of creating a new one. However, you must set up forwarding on the account using the next steps.
Set Up Email Forwarding Within Gmail
Please see Google's instructions on setting up email forwarding.
Insert Your New Gmail Address
Make sure you insert your new Gmail as your sending address under Settings > Store Info.
You can test by sending a receipt to your personal email address. You should receive in either your inbox but it may appear in the Spam folder. If you reply to the email, your reply will be sent to the Gmail account, then immediately forwarded to your primary business email (whatever you set up in your Gmail forwarding options).