Emails

Since the last update i have been getting error messages in returned auto emails, not delivered - stating "messages has lines too long for transport"

where do i start looking , in order to fix this issues

They update would not have caused that. If anything, fix it, especially if you are hosting at godaddy. 

If all emails are doing it then you may have added code to the email header or footer, or email wrapper,  that is not making line breaks. Settings -> Default Emails.