In github the developers are testing the solution to this trouble. It seems that spampd is not updated in ubuntu 18.04. I’m testing the manually update of spampd. To test it i made the following.
In my home folder:
wget https://github.com/mpaperno/spampd/archive/2.53.zip
unzip 2.53.zip
cd spampd-2.53
cp spampd.pl /usr/sbin
cd /usr/sbin
cp spampd spampdold
rm spampd
mv spampd.pl spampd
cd /etc/postfix
nano main.cf
An then i commented the line who I added before,
#lmtp_destination_recipient_limit = 1
I saved the changes an i made
sudo shutdown -r now
It seems that it works well, but i’m still testing.