Calibre Error sending to kindle

Hello,

I seem to have a regular recurring problem after a a software update. Newspapers sent to my kindle via GMX seem to fail to send. I get an error after the fetch downloads the newspapers and after it tries to send to kindle by email. I am using a mac with up to date IOS. would love any advice you may have. I have uninstalled and reinstalled Calibre with no success.

Here is the error:

Starting job: Email New York Times to __________@kindle.com
connect: (u'mail.gmx.com', 587)
connect: (u'mail.gmx.com', 587)
reply: '220 gmx.com (mrgmx102) Nemesis ESMTP Service ready\r\n'
reply: retcode (220); Msg: gmx.com (mrgmx102) Nemesis ESMTP Service ready
connect: gmx.com (mrgmx102) Nemesis ESMTP Service ready
send: 'ehlo gregsteimac1146.lan\r\n'
reply: '250-gmx.com Hello gregsteimac1146.lan [71.90.103.101]\r\n'
reply: '250-AUTH LOGIN PLAIN\r\n'
reply: '250-SIZE 69920427\r\n'
reply: '250 STARTTLS\r\n'
reply: retcode (250); Msg: gmx.com Hello ____________.lan [71.90.103.101]
AUTH LOGIN PLAIN
SIZE 69920427
STARTTLS
send: AUTH
reply: '530 Must issue a STARTTLS command first\r\n'
reply: retcode (530); Msg: Must issue a STARTTLS command first

Sending failed...

Traceback (most recent call last):
File "site-packages/calibre/gui2/email.py", line 44, in run
File "site-packages/calibre/gui2/email.py", line 134, in sendmail
File "site-packages/calibre/utils/smtp.py", line 154, in sendmail
File "site-packages/calibre/utils/smtplib.py", line 647, in login
SMTPAuthenticationError: (530, 'Must issue a STARTTLS command first')