Customer/Recipient not receiving a Botdoc request?

Best way to Troubleshoot Email Requests when using SMTP

Making sure the email was typed correctly
Checking on the SMTP Server (need assistance from the IT) to see if the email was blocked upon sending for some reason, IP could be blocked, content blocked or any other.
Maybe logging into the sending email (noreply@yourbank.com) and check if the email is on the outgoing mail box (this would check if our connection with your SMTP is correct)
Receiving person need to check SPAM Filters, If they use Gmail or other email with smart email box, could automatically send the email to a Newsletter box or Promotion box.
Testing other emails to check if others are receiving is good to double check if it’s an email provider problem or an specific user problem as well.

SMS Requests

Making sure the Number is correct
Customer could have a SPAM Filter app on his phone like Truecaller: ID & spam block – Apps no Google Play that could be filtering the request
We have the logs of the SMS sent, so you could send time and number that was sent so we can check the logs for deliverability
Testing other numbers in the same carrier as the customer and a different carrier as well to see if this could be a carrier issue.