Hi,
By "they are getting the following adreses: EX:adres@domain.com", do you mean they received emails and the senders' address showed like 'EX:adres@domain.com'? If this is the case, does this issue happen to all senders or just certain ones?
Does this issue happen in Outlook? Please also check if the issue persists in OWA.
If this issue only happen in Outlook, please try recreate the OAB and then check if this issue continues. To do this, please follow:
1. Exit Outlook.
2. Navigate to the following path:
C:\Users\%username%\AppData\Local\Microsoft\Outlook
2. Rename .oab file to .old.
3. Restart Outlook and then Outlook will create a new one.
If this issue also exists in OWA, it's more likely a server side issue, I'd recommend you post a new question in the Exchange forum for further assistance:
https://social.technet.microsoft.com/Forums/office/en-US/home?category=exchangeserver
The reason why we recommend posting appropriately is you will get the most qualified pool of respondents, and other partners who read the forums regularly can either share their knowledge
or learn from your interaction with us. Thank you for your understanding.
Regards,
Steve Fan
TechNet Community Support