Linux Setup Guide (Debian, Ubuntu, Rocky Linux, Fedora, openSUSE)

Every example in this repo runs on any of these distributions — the SMTP connection itself (port 587/465, TLS) is identical everywhere. What differs is how you install the prerequisites. This page is a quick reference so you don't have to guess package names per distro.

Don't want to install anything locally at all? Open this repo in the included Dev Container (or as a GitHub Codespace via the badge in the README) — every runtime in the tables below comes preinstalled.

The username and password come from an account, and the account is free. Register at msgwing.com, activate, and copy the generated login and password — they are shown once. Mail leaves from that generated @msgwing.com address rather than your own domain, and the cap is 200 messages a day with no paid tier that lifts it. Both limits are stated here rather than discovered later; if either one rules this out for you, the alternatives page names the tools that do not have them.

Base tools (curl, openssl)

Needed for check-connection.sh and bash-curl-zerosmtp.sh.

Distro	Command
Debian / Ubuntu	sudo apt update && sudo apt install -y curl openssl
Rocky Linux	sudo dnf install -y curl openssl
Fedora	sudo dnf install -y curl openssl
openSUSE	sudo zypper install -y curl openssl

curl and openssl ship preinstalled on most of these distros already — this is only needed for minimal/container base images.

swaks (for bash-swaks-zerosmtp.sh)

swaks isn't in every distro's default repos the same way:

Distro	Command
Debian / Ubuntu	sudo apt install -y swaks
Fedora	sudo dnf install -y swaks (in Fedora's own repos)
Rocky Linux	sudo dnf install -y epel-release && sudo dnf install -y swaks (needs EPEL)
openSUSE	sudo zypper addrepo https://download.opensuse.org/repositories/server:mail/openSUSE_Tumbleweed/server:mail.repo && sudo zypper refresh && sudo zypper install -y swaks (adjust the repo URL for your openSUSE version)

Language runtimes

Only install what you need for the example(s) you're using — see the Code Examples table for which file needs which.

Language	Debian/Ubuntu (apt)	Rocky/Fedora (dnf)	openSUSE (zypper)
Python	python3	python3	python3
PHP + Composer	php-cli composer	php-cli composer	php composer
Node.js / TypeScript	nodejs npm	nodejs npm	nodejs npm
Ruby	ruby	ruby	ruby
Lua	lua5.4 lua-socket lua-sec	lua lua-socket lua-sec	lua54 lua-socket lua-sec
Perl	libio-socket-ssl-perl libauthen-sasl-perl	perl-IO-Socket-SSL perl-Authen-SASL	perl-IO-Socket-SSL perl-Authen-SASL
C (libcurl)	gcc libcurl4-openssl-dev	gcc libcurl-devel	gcc libcurl-devel
Dart	see Dart's install docs — package names vary by distro	same	same
Go	golang-go	golang	go
Java	default-jdk	java-21-openjdk-devel	java-21-openjdk-devel
Kotlin	install Gradle manually (no build needed — gradle build fetches Kotlin itself)	same	same
.NET / C#	see Microsoft's install docs — package names vary by exact distro version	same	same
Rust	curl https://sh.rustup.rs -sSf | sh (via rustup, same on every distro)	same	same
Maven (for the Java example)	maven	maven	maven

Want the whole system to relay through ZeroSMTP?

If you want cron jobs, mail/sendmail, or monitoring tools to send through ZeroSMTP instead of a specific script, see SYSTEM-MTA.md for Postfix (satellite/smarthost mode), msmtp, and Exim4 configuration.

More than one machine

Doing the msmtp setup by hand is fine once. For a fleet, use ansible-zerosmtp.yml, which does the same thing — installs msmtp and the sendmail shim, writes /etc/msmtprc at mode 0600, redirects root's mail to a real address, and verifies the result with msmtp --pretend:

ansible-playbook -i inventory.ini ansible-zerosmtp.yml -e zerosmtp_username=you@msgwing.com -e zerosmtp_password=... -e zerosmtp_from=you@msgwing.com -e zerosmtp_to=alerts@example.com

Keep the password out of your shell history by putting these variables in an ansible-vault file instead and running with --ask-vault-pass.

Connectivity

Everything else — firewall rules, ports, TLS — behaves the same across all five distros; there's nothing distro-specific to configure for outbound SMTP. If a send hangs or times out, it's almost always the network (cloud provider or ISP blocking outbound SMTP), not the OS — run check-connection.sh first and see TROUBLESHOOTING.md.