The captcha thingy could be new to GMX’ server farm in the US and may be rolled out to EU in the near future. I did not hear about till now.
But what exactly
will trigger the captcha question???
Your answer seems a bit short in the following point, so I’m going to ask again:
Will the captcha only happen after a connection problem or did you see this kind of verification w/o transmission problems as well?
--> OK, you enter your credentials, will the capcha verification always be there,
also when your camera did not have connection problems before?
You may have to disable the camera to check this, and log out / in several times.
What I want to find out is if the camera “connection problems” happen and as a result GMX sets a flag to have you verify your account (by the captcha).
You wrote: “… after that my email client is able again …” so this would point to problems when connecting GMX, and GMX thinking about fraudulent connection attempts - but I want to make sure this / our assumption is true.
So your email client is the camera software
If you hit the SMTP limit the GMX server will not send you an email but return an error code + text in the SMTP transaction, you’d need a good email client to read the message (see my above linked posting).
Your camera’s “connection error” message could be translated from Vietnamese to Chinese and to English using Google translate, the true cause could be anything from camera hardware / firmware, your computer / anti virus / network / router / provider to GMX.
No chance to find out without reading the SMTP commands from a log file or a network capture.
< Yea, you may not have changed anything, but think about automated updates and that everything, especially software (settings), will break from time to time >
Changing sender IP is not a problem.
But fact is:
Without any “trigger” the GMX (SMTP) server would not think about abuse or have any reason to flag your account as a security risk.
This trigger is definitely caused by your camera…
--> This is a blatant assumption
, as it could be your mobile, your friend, a virus, …
or anything and anybody misusing your (the same) GMX account !!!
To find out if your account is blocked from sending because of too many SMTP messages
(the SMTP limit, remember: 11 recipients per hour
You need to wait for the connection problem,
to log in (with captcha) to your account
and try to send an email message.
If it’s the limit you will see a pop up in the web interface (see my above linked posting) and the message will not be sent.