Is this a postfix problem? Receiving mail from cellphone

[Dan Coutu]

This is a RHEL server running postfix.

Sending email to the server from my cell phone is giving an error and I 
don't understand why. I'm hoping that someone here can shed light on it 
for me.

Here's the mail log entries that show the problem:

Dec  1 01:55:27 ec2-75-101-156-55 postfix/smtpd[31695]: connect from 
150.sub-69-78-129.myvzw.com[69.78.129.150]
Dec  1 01:55:27 ec2-75-101-156-55 postfix/smtpd[31695]: NOQUEUE: reject: 
RCPT from 150.sub-69-78-129.myvzw.com[69.78.129.150]: 450 4.7.1 
<njbrspamp5.vtext.com>: Helo command rejected: Host not found; 
from=<8023094781 at VTEXT.COM> to=<register at celltography.com> proto=ESMTP 
helo=<njbrspamp5.vtext.com>
Dec  1 01:55:32 ec2-75-101-156-55 postfix/smtpd[31695]: disconnect from 
150.sub-69-78-129.myvzw.com[69.78.129.150]

Thanks for any help or pointers to resolving this.

Dan