It works ! Thanks a lot vinsan !
After doing this I also had this problem. I fixed it following the solution in the comments.
Here is the content of my /etc/postfix
drwxr-xr-x 3 root root 4096 août 21 03:06 .
drwxr-xr-x 128 root root 12288 août 21...
I've juste followed the Ubuntu 16.04 perfect server guide. Everything seems to work except one thing : I can't receive any email. But I...
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