There are few steps you can take
Double check that you are sending to the right address
This may seem obvious but hear me out. We all make mistakes. If you keep sending emails that get bounced for this or any other reason, it can hurt your sender reputation and get you on a blacklist.
Check to see if you have been put on a spam filter blacklist
It is easy to check as there are few tools like MX Toolbox, and Return Path that can help you with this. Once you know which spam filters your domain has been blocked by, you can find out how to remove it.
Use this service and follow recommendations
Create a new email address with a service like Gmail to test your domain reputation
try sending email to this new address to see if your emails are being received
Use another medium to check if the recipient has the emails you have been sending
This way you will know if your emails have been getting through. Additionally, your recipient has been deleting them because they looked like spam. For tips on how to avoid spammy emails, read Avoid the spam folder: Get your Customers to
Read your Cold Email
Check if the content would trigger a spam filter
There are certain patterns that you find in spam, from lots of links or pictures without much unlinked text to crazy formatting and spelling /grammar mistakes (Really, they check that!). For more information about what can set off your spam filter, read How To Avoid Email Spam Filters When Sending Sales Outreach Emails.
Good luck.