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If you are on the essentials package of Sendgrid and experiencing deliverability issues, we recommend upgrading to the Pro package from the essentials package. It's $80 a month, but it comes with a dedicated IP, which basically means that your deliverability isn't up to the fate of all the senders lumped in the same IP as you, but you can have control over your own reputation because your IP, and sender reputation, is yours.
When creating test users and doing testing, send to real email addresses. If you need to create a bunch of accounts, we do too, the Aspenware team uses the gmail trick to create an unlimited number of real email addresses. Simply use the + sign after your email domain (jennibuonanni) and before @gmail.com and enter whatever you want between the + and @. So jennibuonanni+tester1@gmail.com will actually be send to my gmail account, as will jennibuonanni+supportrulz@gmail.com. You can also use Mailinator.
If you are still experiencing email deliverability issues, you may want to look into sender authentication through Sendgrid. The three levers that can help improve your Sender authentication are setting up DNS, DKIM and SPF. Before going down this route, you will want to get access make changes to your DNS, or work with someone who can. Your networking/IT group can likely help with this.
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