Nice hack to see if a Blackberry device is getting email.
Send them an email with a subject line of just:
<confirm>
After it gets to the phone, it will do an auto-reply with:
Subject: BlackBerry Delivery Confirmation Your message: TO: blahblah@yourdomain.ack SENT: Fri Apr 22 14:58:54 2017 Eastern Daylight Time SUBJECT: <confirm> has been delivered to the recipient's BlackBerry Handheld.