Good Day,
when sending out emails to google users, by using a SMTP server (non-google), emails are getting rejected due to duplicated header.
This is the mail system at host XXXXXXXXXXXXX.
I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below.
For further assistance, please send mail to postmaster.
If you do so, please include this problem report. You can
delete your own text from the attached returned message.
The mail system
XXXXXX@gmail.com: host gmail-smtp-in.l.google.com[173.194.194.26] said:
550-5.7.1 [84.16.66.175] Our system has detected that this message is not
RFC 550-5.7.1 5322 compliant: duplicate headers. To reduce the amount of
spam sent 550-5.7.1 to Gmail, this message has been blocked. Please review
550 5.7.1 RFC 5322 specifications for more information.
c25-20020a5d8b59000000b006a0e6aab3a2si5501851iot.80 - gsmtp (in reply to
end of DATA command)
If I unflag the RTF format in osticket, then emails are being accepted by google.

Thanks
Maurizio