Script install on Ubuntu 20.04 fail Postfix

I try to install but have this error, last week work fine the script but today no work any more.

Reading package lists… Done
Building dependency tree
Reading state information… Done
libffi-dev is already the newest version (3.3-4).
python3-dev is already the newest version (3.8.2-0ubuntu2).
python3-setuptools is already the newest version (45.2.0-1).
build-essential is already the newest version (12.8ubuntu1.1).
git is already the newest version (1:2.25.1-1ubuntu3.1).
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
1 not fully installed or removed.
After this operation, 0 B of additional disk space will be used.
Setting up postfix (3.4.13-0ubuntu1) …

Postfix ( configuration was not changed. If you need to make changes,
edit /etc/postfix/ (and others) as needed. To view Postfix
configuration values, see postconf(1).

After modifying, be sure to run ‘systemctl reload postfix’.

Running newaliases
newaliases: warning: valid_hostname: numeric hostname:
newaliases: fatal: file /etc/postfix/ parameter mydomain: bad parameter value:
dpkg: error processing package postfix (–configure):
installed postfix package post-installation script subprocess returned error exit status 75
Processing triggers for libc-bin (2.31-0ubuntu9.2) …
Errors were encountered while processing:
E: Sub-process /usr/bin/dpkg returned an error code (1)