Incorrect advice that tykhe.biz is not a valid domain

Occasionally I get this message, which is incorrect, I have been successfully sending to tykhe.biz for many years. Why do you occasionally refuse to send ? Nb. in this example I have deleted the name of my correspondent xxxx for privacy reasons.
Quote …
The following recipient(s) cannot be reached:

xxxx@tykhe.biz’ - 5.1.2 Invalid domain: tykhe.biz

Why do you deny transmission ?

I have been successfully sending to tykhe.biz for many years. Why do you occasionally refuse to send ?

  • 5.1.2 Invalid domain: tykhe.biz

From that error sounds like the domain @.biz is possibly not allways online or not available ?.

I would suggest to contact the domain tykhe.biz webmaster or website technical support and advise them the error you get when sending.

Apart from the domain name itself, It can also be related to “resolving of the domain name”. Eg: when one of the servers along the way (to the destination) is unable to resolve the domain.

So in my opinion it’s nothing normally to do with the mail client as it works most of the time, and more likely domain related problem somewhere.

This message comes from your server, not eM Client. The message is successfully uploaded to your email provider, but they can’t deliver it to that domain.