Email to @kindle.com failed

Hi,

I posted this before, but in the wrong forum. Hope this is the right one.

Where for years I was able to send books to my @kindle email address and then wifi them to my Kindle, this stopped a few months ago.

I use my gmail account in the Calibre Preferences setup. When I sent from gmail to my @kindle.com account it works fine, but when I send from Calibre I get the error log as below.

Any idea what I am doing wrong?

TIA
Gert

Starting job: Email The Economist to gertblij@kindle.com

Sending failed...

Traceback (most recent call last):
File "site-packages\calibre\gui2\email.py", line 43, in run
File "site-packages\calibre\gui2\email.py", line 130, in sendmail
File "site-packages\calibre\utils\smtp.py", line 116, in sendmail
File "site-packages\calibre\utils\smtp.py", line 108, in sendmail_direct
IOError: Failed to send mail: error(10060, 'A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond')


Retrying in 1 seconds...

Waiting 1 seconds before sending, to avoid being marked as spam.
You can control this delay via Preferences->Tweaks

Sending failed...

Traceback (most recent call last):
File "site-packages\calibre\gui2\email.py", line 43, in run
File "site-packages\calibre\gui2\email.py", line 130, in sendmail
File "site-packages\calibre\utils\smtp.py", line 116, in sendmail
File "site-packages\calibre\utils\smtp.py", line 108, in sendmail_direct
IOError: Failed to send mail: error(10060, 'A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond')

Job: "Email The Economist to gertblij@kindle.com" failed with error:
Traceback (most recent call last):
File "site-packages\calibre\gui2\threaded_jobs.py", line 83, in start_work
File "site-packages\calibre\gui2\email.py", line 98, in __call__
IOError: Failed to send mail: error(10060, 'A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond')

Called with args: (u'C:\\Users\\gert\\AppData\\Local\\Temp\\calibre_ yriiqw\\wfsklocaltmpfmt.mobi', u'The Economist - calibre.mobi', u'gertblij@kindle.com', u'E-book: The Economist', u'Attached, you will find the e-book\n\nThe Economist\n\tby calibre\n\nin the MOBI format.') {u'log': <calibre.utils.logging.GUILog object at 0x000000000AE84860>, u'abort': <threading._Event object at 0x000000000AE84128>, u'notifications': <Queue.Queue instance at 0x0000000009219D08>}