invalid MAIL FROM email address using "sendmail -t"

[Edwin Grubbs]

When using ssmtp with the "sendmail -t" command to override the from address, it uses
  MAIL FROM:<from: <email address hidden>>
instead of
  MAIL FROM: <email address hidden>

Postfix will actually accept this bogus email address, but gmail will not.

Here is the debugging output of the command showing the invalid MAIL FROM.

$ sendmail -t -d9
from: <email address hidden>
to: <email address hidden>
subject: test has-dev

[<-] 220 mouthwateringmedia.com ESMTP Postfix (Ubuntu)
[->] EHLO has-dev.mouthwateringmedia.com
[<-] 250 DSN
[->] STARTTLS
[<-] 220 2.0.0 Ready to start TLS
[->] HELO has-dev.mouthwateringmedia.com
[<-] 250 mouthwateringmedia.com
[->] MAIL FROM:<from: <email address hidden>>

Here is my /etc/ssmtp/ssmtp.conf.

<email address hidden>
mailhub=HIDDEN:587
rewriteDomain=mouthwateringmedia.com
hostname=has-dev.mouthwateringmedia.com
FromLineOverride=YES
UseTLS=YES
UseSTARTTLS=YES

$ lsb_release -rd
Description: Ubuntu 14.04.4 LTS
Release: 14.04

$ apt-cache policy ssmtp
ssmtp:
  Installed: 2.64-7
  Candidate: 2.64-7
  Version table:
 *** 2.64-7 0
        500 http://us.archive.ubuntu.com/ubuntu/ trusty/universe amd64 Packages
        100 /var/lib/dpkg/status