Types of web servers and the software they run

A web server is the software that listens for HTTP/HTTPS requests and returns web pages to browsers. For email, it matters more than people expect: the web server is where users read their mail (webmail), where they send you messages (contact forms), and where every “we'll email you a confirmation” begins. It is the front door of communication with your users — the website asks, and email follows up.

1. Web server vs. application server vs. reverse proxy

The word “server” covers a few roles that usually run together:

• Web (HTTP) server — speaks HTTP, serves pages and static files. Examples: Nginx, Apache, LiteSpeed, IIS, Caddy.
• Application server — runs the program that generates the page and triggers emails (sign-up confirmations, password resets). Examples: PHP-FPM, Apache Tomcat, Gunicorn, Node.js.
• Reverse proxy / load balancer — sits in front, terminates TLS, caches, spreads traffic. Nginx, HAProxy, Envoy, Caddy; CDNs like Cloudflare play this role too.

2. The web server software you'll actually meet

3. How web servers display mail and talk to your users

This is where web servers and email meet directly:

• Webmail — clients like Roundcube, SOGo and Rainloop/Snappymail are web apps. A web server (Apache/Nginx) renders your inbox in the browser; behind it, an IMAP server holds the actual messages.
• Contact & sign-up forms — when a visitor writes to you, the web app on the web server hands the message to a mail server to deliver. The form is the website's half; the email is the follow-up.
• Transactional email — confirmations, receipts, password resets and alerts are triggered by code running on the application server, then sent through an MTA or an API (Amazon SES, SendGrid…).
• HTML email rendering — the same HTML/CSS skills that build web pages build the emails your users receive; the message is effectively a tiny web page delivered to an inbox.

4. Web server ≠ mail server

A domain's website and its email are delivered by different servers, pointed to by different DNS records. The web server is found through A/AAAA records (browsers, HTTP); the mail server is found through MX records (other mail servers, SMTP). A site can have a flawless website and no working email at all — or the reverse.

That is why a fast website tells you nothing about whether someone@theirdomain.com can receive mail. To inspect the mail side, use our MX Lookup and the email checker; to learn about the mail side's software, see types of email servers.

5. How to tell which web server a site uses

Most web servers announce themselves in the Server response header:

curl -I https://example.com

HTTP/2 200
server: nginx
content-type: text/html; charset=UTF-8

Operators can hide or fake this header, and a CDN often reports its server instead of the origin's — so treat it as a strong hint, not proof. The same idea applies on the mail side: an SMTP server's greeting banner usually names its software too.