Resolve "Anyone can send mails from a local user as long as the recipient is another local user"

use apt-get to install packages

This fixes the output "WARNING: apt does not have a stable CLI interface. Use with caution in scripts."

Only call deploy hook when mail cert is renewed

Typo in my last merge

Update emailwiz.sh

New line in the final output, looks way better!

use domain instead of @

Reset umask to 0022 at beginning of install

Fix: #178 leakage of public IP addresses in sent emails

Prevented escape shell

Some strings will escape and break the script, inserted fixes like single quotes ( ' ' ).

Update README.md

Replaced 933 for 993, the correct port for IMAP.