Migrating Exchange 2007 to Office 365, Go-Daddy Hosted Website, How many SSL's do I need?

My setup is Windows 2008 server, with locally hosted Exchange 2007.  I'm trying to migrate to Office 365 Business Essentials on a cutover migration.  To do this, I've learned I need to enable Outlook Anywhere.  To do that I need an SSL.  Right now our email addresses are firstname.lastname@webdomain.org  Webdomain is registered through GoDaddy who also hosts our web site.  We have a MX record that directs our email to mail.webdomain.org and an A record for host mail that points to our static IP.  We currently have no SSL certificate anywhere that I can find.    I don't know how many SSL's I need, and I don't know how to make sure I'm requesting them correctly to make sure I'm covered for the migration.  I don't even know if I will need one for any longer than it takes to migrate to Office 365.  Can someone help point me in the right direction?
Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Seth SimmonsSr. Systems AdministratorCommented:
either get a wildcard cert or make sure all of the host names are part of the cert SAN

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
You will require a single name third party SSL certificate to migrate Exchange 2007 to Office 365. then enable outlook anywhere using that url e.g mail.domain.com.

To create the CSR you can follow godaddy link as below.

It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today

From novice to tech pro — start learning today.