People doing email marketing have come across this many a times. Even after setting up your reverse DNS, SPF, DKIM records as well as setting up DMARC policy your email may not be arriving into the user’s inbox. It may be going into the spam/junk mail folder and your recipient may be oblivious to this fact as normally no one checks his/her spam folder for emails. The sender in this case should follow up the recipient via phone/Whatsapp or any other contact method besides email and tell them to check their spam/junk mail folder as well so they don’t miss out on the email.
If your recipient is a GMail user then you can ask them to take the steps below to remove your email from the Spam folder and instruct GMail to deliver the email to the recipient’s inbox.
Once you perform the above steps the chances of your email going into the recipient’s inbox increases.
Hope the above helped. If you need my help in resolving any email issue then do contact me