diff --git a/README.md b/README.md
index c5988de..f5aab45 100644
--- a/README.md
+++ b/README.md
@@ -214,6 +214,9 @@ These are the variables that you MUST change in your docker-compose.yaml before
 - `SMTP_PORT`	: use this port. 25, 587, whatever your host asks for.
 - `SMTP_HOST_USER`: authenticate this user
 - `SMTP_HOST_PASSWORD`: and use this password
+- `SMTP_SECURE_MODE`: security mode for smtp connection - can be `smtp` (no encryption), `smtps` or `starttls`
+- `SMTP_VERIFY_HOSTNAME`: defaults to `true` - verify, that certificate hostname is identical to `SMTP_HOST`
+- `SMTP_VERIFY_CERT`: defaults to `true` - verify, that certificate is valid
 
 For more details on how to configure this image, please look [Mailman-core's
 Readme](core/)
diff --git a/core/README.md b/core/README.md
index ec55bbc..52f6a10 100644
--- a/core/README.md
+++ b/core/README.md
@@ -60,6 +60,8 @@ standard version of docker-compose.yaml from this repository.
 
 - `SMTP_PORT`: Port used for SMTP. Default is `25`.
 
+- `SMTP_SECURE_MODE`: Security mode (encryption) used for SMTP. Default is `smtp`. Can also be `starttls` or `smtps`.
+
 - `HYPERKITTY_URL`: Default value is `http://mailman-web:8000/hyperkitty`
 
 In case of a need for fine tuning of REST API web-server that uses [Gunicorn](https://docs.gunicorn.org/en/stable/settings.html) (e.g. for raising of timeouts) `/opt/mailman/core/gunicorn-extra.cfg` file could be provided holding necessary configuration options.
@@ -106,6 +108,9 @@ lmtp_host: $MM_HOSTNAME
 lmtp_port: 8024
 smtp_host: $SMTP_HOST
 smtp_port: $SMTP_PORT
+smtp_secure_mode: $SMTP_SECURE_MODE
+smtp_verify_hostname: $SMTP_VERIFY_HOSTNAME
+smtp_verify_cert: $SMTP_VERIFY_CERT
 configuration: python:mailman.config.exim4
 
 [runner.retry]
diff --git a/core/docker-entrypoint.sh b/core/docker-entrypoint.sh
index d0bd089..3e544bb 100755
--- a/core/docker-entrypoint.sh
+++ b/core/docker-entrypoint.sh
@@ -43,6 +43,18 @@ if [[ ! -v SMTP_PORT ]]; then
 	export SMTP_PORT=25
 fi
 
+if [[ ! -v SMTP_SECURE_MODE ]]; then
+	export SMTP_SECURE_MODE="smtp"
+fi
+
+if [[ ! -v SMTP_VERIFY_HOSTNAME ]]; then
+	export SMTP_VERIFY_HOSTNAME="true"
+fi
+
+if [[ ! -v SMTP_VERIFY_CERT ]]; then
+	export SMTP_VERIFY_CERT="true"
+fi
+
 # Check if REST port, username, and password are set, if not, set them
 # to default values.
 if [[ ! -v MAILMAN_REST_PORT ]]; then
@@ -144,6 +156,9 @@ smtp_host: $SMTP_HOST
 smtp_port: $SMTP_PORT
 smtp_user: $SMTP_HOST_USER
 smtp_pass: $SMTP_HOST_PASSWORD
+smtp_secure_mode: $SMTP_SECURE_MODE
+smtp_verify_hostname: $SMTP_VERIFY_HOSTNAME
+smtp_verify_cert: $SMTP_VERIFY_CERT
 configuration: python:mailman.config.exim4
 
 EOF
@@ -167,6 +182,9 @@ smtp_host: $SMTP_HOST
 smtp_port: $SMTP_PORT
 smtp_user: $SMTP_HOST_USER
 smtp_pass: $SMTP_HOST_PASSWORD
+smtp_secure_mode: $SMTP_SECURE_MODE
+smtp_verify_hostname: $SMTP_VERIFY_HOSTNAME
+smtp_verify_cert: $SMTP_VERIFY_CERT
 configuration: /etc/postfix-mailman.cfg
 
 EOF
diff --git a/postorius/Dockerfile b/postorius/Dockerfile
index 93eaca8..ec4f3d6 100644
--- a/postorius/Dockerfile
+++ b/postorius/Dockerfile
@@ -6,9 +6,9 @@ FROM alpine:3.20.0
 # rights for management script
 RUN --mount=type=cache,target=/root/.cache \
     set -ex \
-	&& apk add --no-cache --virtual .build-deps gcc libc-dev linux-headers libldap \
+	&& apk add --no-cache --virtual .build-deps gcc libc-dev linux-headers \
 		postgresql-dev mariadb-dev mariadb-connector-c python3-dev libffi-dev openldap-dev cargo rust \
-	&& apk add --no-cache --virtual .mailman-rundeps bash sassc tzdata \
+	&& apk add --no-cache --virtual .mailman-rundeps bash sassc tzdata libldap \
 		postgresql-client mysql-client py3-mysqlclient curl mailcap gettext \
 		python3 py3-pip libffi libuuid pcre-dev py-cryptography \
 	&& python3 -m pip install --break-system-packages -U 'Django<4.3' pip setuptools wheel \
diff --git a/postorius/Dockerfile.dev b/postorius/Dockerfile.dev
index b80a66c..989ec98 100644
--- a/postorius/Dockerfile.dev
+++ b/postorius/Dockerfile.dev
@@ -10,9 +10,9 @@ ARG CLIENT_REF
 # rights for management script
 RUN --mount=type=cache,target=/root/.cache \
     set -ex \
-	&& apk add --no-cache --virtual .build-deps gcc libc-dev linux-headers libldap \
+	&& apk add --no-cache --virtual .build-deps gcc libc-dev linux-headers \
 		postgresql-dev mariadb-dev mariadb-connector-c python3-dev libffi-dev git cargo rust \
-	&& apk add --no-cache --virtual .mailman-rundeps bash sassc tzdata \
+	&& apk add --no-cache --virtual .mailman-rundeps bash sassc tzdata libldap \
 		postgresql-client mysql-client py3-mysqlclient curl mailcap \
 		python3 py3-pip libffi gettext py-cryptography \
     && python3 -m pip install --break-system-packages -U pip setuptools wheel \
diff --git a/web/Dockerfile b/web/Dockerfile
index 2c2f464..37deeba 100644
--- a/web/Dockerfile
+++ b/web/Dockerfile
@@ -9,9 +9,9 @@ COPY requirements.txt /tmp/
 # rights for management script
 RUN --mount=type=cache,target=/root/.cache \
     set -ex \
-	&& apk add --no-cache --virtual .build-deps gcc libc-dev linux-headers libldap \
+	&& apk add --no-cache --virtual .build-deps gcc libc-dev linux-headers \
            postgresql-dev mariadb-dev mariadb-connector-c python3-dev libffi-dev openldap-dev cargo rust \
-	&& apk add --no-cache --virtual .mailman-rundeps bash sassc tzdata \
+	&& apk add --no-cache --virtual .mailman-rundeps bash sassc tzdata libldap \
 	   postgresql-client mysql-client py3-mysqlclient curl mailcap gettext \
 	   python3 py3-pip xapian-core xapian-bindings-python3 libffi pcre-dev py-cryptography \
 	&& python3 -m pip install --break-system-packages -U 'Django<4.3' pip setuptools wheel \
diff --git a/web/Dockerfile.dev b/web/Dockerfile.dev
index 7c93f3c..b629441 100644
--- a/web/Dockerfile.dev
+++ b/web/Dockerfile.dev
@@ -11,9 +11,9 @@ ARG CLIENT_REF
 # rights for management script
 RUN --mount=type=cache,target=/root/.cache \
     set -ex \
-    && apk add --no-cache --virtual .build-deps gcc libc-dev linux-headers git libldap \
+    && apk add --no-cache --virtual .build-deps gcc libc-dev linux-headers git \
         postgresql-dev mariadb-dev mariadb-connector-c python3-dev libffi-dev openldap-dev cargo rust \
-    && apk add --no-cache --virtual .mailman-rundeps bash sassc pcre-dev tzdata \
+    && apk add --no-cache --virtual .mailman-rundeps bash sassc pcre-dev tzdata libldap \
         python3 py3-pip postgresql-client mysql-client py3-mysqlclient \
         curl mailcap xapian-core xapian-bindings-python3 libffi gettext py-cryptography \
     && python3 -m pip install --break-system-packages -U pip setuptools wheel \
diff --git a/web/requirements.txt b/web/requirements.txt
index e6dcc61..9d54fee 100644
--- a/web/requirements.txt
+++ b/web/requirements.txt
@@ -1,4 +1,4 @@
 mailmanclient==3.3.5
 postorius==1.3.10
 hyperkitty==1.3.9
-django-mailman3==1.3.11
\ No newline at end of file
+django-mailman3==1.3.12
\ No newline at end of file