E-Mail in general is very unique to each individual user. Gmail for example has four different Inbox tabs and of course the notorious junk/spam mail folder. Almost every e-mail provider also comes with the option to create filters that could inadvertently put e-mail where it doesn't belong.
One thing every e-mail platform has is the option to search for mail. There are two things that you could search for that'll help you find the onboard e-mail:
The e-mail comes from: [email protected]
The subject of the e-mail is: Let's Get Your Onboard Completed
Note: You may need to go into your junk/spam folder to do do this search.
If this doesn't help and you are ready to begin your onboard process you can call the team at (888) 995-4658 and we will help get you to where you need to go to complete the process.