First and foremost, welcome to our Community!  @PolderPhantom 

I understand that it is not convenient to have to change your e-mail address. However, we can only use @odido.nl for our services. 

Did You read my message?  

So, you are telling me that since the move for t-mobile you can not receive emails for outside the company !

secondly i have used a .t-mobile email address, not once.  But your system is sending me messages saying i have. 
 

I suggest you forward this information to someone who can understand and take responsibility for system errors 

@PolderPhantom I am not sure I understand exactly what you mean by ‘you cannot receive emails for outside the company’, could you elaborate? 

To answer your second question, if you have never used the e-mail before, you can ignore the message. 

Very simple;

i send you an email from gmail.com

you tell me i need to change my email from tmobile to odido. Ok but it was it was gmail not tmobil!

I complain and you guys say “ we can only use @odido.nl for our services.”

does that help ? 

@Teresa van Odido  What is even more sad / funny is you own emails are being sent to me via t-moble accounts !  - see screen shot