You wrote - When I start to write an e-mail,with the first letter it starts to guess my receiver name which is not in my list.
Writing of mails is done , by opening the new compose mail window ( use command and N keys ) .
In the two field when you type a single word say " a " it will show all mail addresses starting with it , as they are all saved in previous recipients list , you have to select the desired mail address to save in to fields .
Even the old recipient is removed .
And if there are multiple contacts then you have do edit them separately .
Or you have to check the mail address by clicking on window > Previous recipients and in its search bar type the mail address or can search by name and remove from the list .