now it can make self-signed certs, turn some settings into options

-- the change to the apt-get install part at the beginning forces an uninstall and purge of configs. This means that if you re-run the script it will "reset" the install to default state by deleting packages and configs and re-installing and re-generating the configs.

--I turned some hardcoded settings into options that can be set in the variables at the top of the script (for convenience). The default behavior is the same as before.
allow_suboptimal_ciphers="yes" #yes no
mailbox_format="maildir" # maildir sdbox
allowed_protocols=" imap pop3 "  #imap pop3

--added a setting "selfsigned="no" # yes no" to choose between  "let's get a cert from letsencrypt" and "create self-signed cert that lasts 100 years", and added the logic to generate the certs and whatnot.
My usecase is for an "isolated" server that collects notifications from devices in the same local network(s) or serves as secure/private messaging system over VPN (wireguard or whatever).
The default is still as before. If creating a self-signed cert is selected, it will show the certificate creation wizard as normal.

--added a few setting variables  to auto-generate the certificate with country name, state/province name, organization name and hostname
Again this is not enabled by default.

emailwiz.sh

@@ -17,37 +17,96 @@
 
 umask 0022
 
-apt-get install -y postfix postfix-pcre dovecot-imapd dovecot-pop3d dovecot-sieve opendkim opendkim-tools spamassassin spamc net-tools fail2ban
+install_packages="postfix postfix-pcre dovecot-imapd dovecot-pop3d dovecot-sieve opendkim opendkim-tools spamassassin spamc net-tools fail2ban"
+
+systemctl -q stop dovecot
+systemctl -q stop postfix
+apt-get purge ?config-files -y $install_packages
+apt-get install -y $install_packages
+
 domain="$(cat /etc/mailname)"
 subdom=${MAIL_SUBDOM:-mail}
 maildomain="$subdom.$domain"
 certdir="/etc/letsencrypt/live/$maildomain"
 
-# Open required mail ports, and 80, for Certbot.
-for port in 80 993 465 25 587; do
+selfsigned="no" # yes no
+allow_suboptimal_ciphers="yes" #yes no
+mailbox_format="maildir" # maildir sdbox
+allowed_protocols=" imap pop3 "  #imap pop3
+
+use_cert_config="no"
+country_name="" # IT US UK IN etc etc
+state_or_province_name=""
+organization_name=""
+common_name="$( hostname -f )"
+
+if [ "$use_cert_config" = "yes" ]; then
+	echo "[req]
+	default_bit = 4096
+	distinguished_name = req_distinguished_name
+	prompt = no
+
+	[req_distinguished_name]
+	countryName             = $country_name
+	stateOrProvinceName     = $state_or_province_name
+	organizationName        = $organization_name
+	commonName              = $common_name " > $certdir/certconfig.conf
+
+fi
+
+# Open required mail ports
+for port in 993 465 25 587; do
 	ufw allow "$port" 2>/dev/null
 done
 
-[ ! -d "$certdir" ] &&
-	possiblecert="$(certbot certificates 2>/dev/null | grep "Domains:\.* \(\*\.$domain\|$maildomain\)\(\s\|$\)" -A 2 | awk '/Certificate Path/ {print $3}' | head -n1)" &&
-	certdir="${possiblecert%/*}"
-
-[ ! -d "$certdir" ] &&
-	certdir="/etc/letsencrypt/live/$maildomain" &&
-	case "$(netstat -tulpn | grep ":80\s")" in
-	*nginx*)
-		apt install -y python3-certbot-nginx
-		certbot -d "$maildomain" certonly --nginx --register-unsafely-without-email --agree-tos
-		;;
-	*apache*)
-		apt install -y python3-certbot-apache
-		certbot -d "$maildomain" certonly --apache --register-unsafely-without-email --agree-tos
-		;;
-	*)
-		apt install -y python3-certbot
-		certbot -d "$maildomain" certonly --standalone --register-unsafely-without-email --agree-tos
-		;;
-esac
+if [ "$selfsigned" = "yes" ]; then
+	rm -f $certdir/privkey.pem
+	rm -f $certdir/csr.pem
+	rm -f $certdir/fullchain.pem
+
+	echo "Generating a 4096 rsa key and a self-signed certificate that lasts 100 years"
+	mkdir -p $certdir
+	openssl genrsa -out $certdir/privkey.pem 4096
+
+	if [ "$use_cert_config" = "yes" ]; then
+		openssl req -new -key $certdir/privkey.pem -out $certdir/csr.pem -config $certdir/certconfig.conf
+	else
+		openssl req -new -key $certdir/privkey.pem -out $certdir/csr.pem
+	fi
+	openssl req -x509 -days 36500 -key $certdir/privkey.pem -in $certdir/csr.pem -out $certdir/fullchain.pem
+else
+
+	# Open port 80 for Certbot.
+	ufw allow 80 2>/dev/null
+
+	[ ! -d "$certdir" ] &&
+		possiblecert="$(certbot certificates 2>/dev/null | grep "Domains:\.* \(\*\.$domain\|$maildomain\)\(\s\|$\)" -A 2 | awk '/Certificate Path/ {print $3}' | head -n1)" &&
+		certdir="${possiblecert%/*}"
+
+	[ ! -d "$certdir" ] &&
+		certdir="/etc/letsencrypt/live/$maildomain" &&
+		case "$(netstat -tulpn | grep ":80\s")" in
+		*nginx*)
+			apt install -y python3-certbot-nginx
+			certbot -d "$maildomain" certonly --nginx --register-unsafely-without-email --agree-tos
+			;;
+		*apache*)
+			apt install -y python3-certbot-apache
+			certbot -d "$maildomain" certonly --apache --register-unsafely-without-email --agree-tos
+			;;
+		*)
+			apt install -y python3-certbot
+			certbot -d "$maildomain" certonly --standalone --register-unsafely-without-email --agree-tos
+			;;
+	esac
+
+fi
+
+[ ! -f "$certdir/fullchain.pem" ] && echo "Error locating or installing SSL certificate." && exit 1
+[ ! -f "$certdir/privkey.pem" ] && echo "Error locating or installing SSL certificate." && exit 1
+if [ "$selfsigned" != "yes" ]; then
+	[ ! -f "$certdir/cert.pem" ] && echo "Error locating or installing SSL certificate." && exit 1
+fi
 
 [ ! -d "$certdir" ] && echo "Error locating or installing SSL certificate." && exit 1
 
@@ -62,7 +121,9 @@ postconf -e 'mydestination = $myhostname, $mydomain, mail, localhost.localdomain
 # Change the cert/key files to the default locations of the Let's Encrypt cert/key
 postconf -e "smtpd_tls_key_file=$certdir/privkey.pem"
 postconf -e "smtpd_tls_cert_file=$certdir/fullchain.pem"
-postconf -e "smtp_tls_CAfile=$certdir/cert.pem"
+if [ "$selfsigned" != "yes" ]; then
+	postconf -e "smtp_tls_CAfile=$certdir/cert.pem"
+fi
 
 # Enable, but do not require TLS. Requiring it with other server would cause
 # mail delivery problems and requiring it locally would cause many other
@@ -80,8 +141,10 @@ postconf -e 'smtpd_tls_protocols = !SSLv2, !SSLv3, !TLSv1, !TLSv1.1'
 postconf -e 'smtp_tls_protocols = !SSLv2, !SSLv3, !TLSv1, !TLSv1.1'
 
 # Exclude suboptimal ciphers.
-# postconf -e 'tls_preempt_cipherlist = yes'
-# postconf -e 'smtpd_tls_exclude_ciphers = aNULL, LOW, EXP, MEDIUM, ADH, AECDH, MD5, DSS, ECDSA, CAMELLIA128, 3DES, CAMELLIA256, RSA+AES, eNULL'
+if [ "$allow_suboptimal_ciphers" = "no" ]; then
+	postconf -e 'tls_preempt_cipherlist = yes'
+	postconf -e 'smtpd_tls_exclude_ciphers = aNULL, LOW, EXP, MEDIUM, ADH, AECDH, MD5, DSS, ECDSA, CAMELLIA128, 3DES, CAMELLIA256, RSA+AES, eNULL'
+fi
 
 # Here we tell Postfix to look to Dovecot for authenticating users/passwords.
 # Dovecot will be putting an authentication socket in /var/spool/postfix/private/auth
@@ -164,7 +227,7 @@ ssl_dh = </usr/share/dovecot/dh.pem
 auth_mechanisms = plain login
 auth_username_format = %n
 
-protocols = \$protocols imap pop3
+protocols = \$protocols $allowed_protocols
 
 # Search for valid users in /etc/passwd
 userdb {
@@ -177,7 +240,7 @@ passdb {
 
 # Our mail for each user will be in ~/Mail, and the inbox will be ~/Mail/Inbox
 # The LAYOUT option is also important because otherwise, the boxes will be \`.Sent\` instead of \`Sent\`.
-mail_location = maildir:~/Mail:INBOX=~/Mail/Inbox:LAYOUT=fs
+mail_location = $mailbox_format:~/Mail:INBOX=~/Mail/Inbox:LAYOUT=fs
 namespace inbox {
 	inbox = yes
 	mailbox Drafts {