Cookie header issue OC V1 - HTTP ERROR 431 on hyperlink

Description of job/position

the job is: to find out what is causing HTTP ERROR 431 on the e-mail hyperlink. 

I myself can not reproduce the issue. however, users of my client websites intranet receive a blogpost email, and some complain about the hyperlink which is causing the 431 error. 

after removing cookies from the browser the link works again. 

Is there something wrong with the header cookies? 

Experience & Requirements

 am looking for a developer with enough knowledge of header cookies. Because I have none. 

reproducing the error is impossible or will be hard, therefore knowledge of correct header cookie settings is asked. 


make sure all intranet users will not be affected by development and also make sure they will not receive any test e-mails.