If you don't want to use an email testing tool, you can always email yourself or a colleague. This is the most straightforward way to test emails – their functionality, formatting, links and attachments.  Some free browser extensions allow you to send and receive emails directly from your browser. Another option is an online service that lets you send mail to the provided email address. In return, you receive a score based on such factors as spam filters, DKIM/SPF records and content.