Web servers (nginx, Apache, IIS) and email servers (Postfix, Exchange) are the two most common enterprise server roles. Architecture choices determine throughput, failure modes, and SaaS-vs-self-host trade-offs.
3.5 Web and Email Servers
Web server comparison
Server
Strengths
Typical use
nginx
Lightweight, event-driven
Most common default
Apache
Modular, .htaccess flexibility
Traditional PHP shops
IIS
Windows ecosystem + AD integration
Microsoft stack
Caddy
Auto-HTTPS via Let's Encrypt
Modern small projects
HAProxy
High-throughput L4 + L7 LB
LB and reverse proxy
Envoy
Cloud-native; service mesh data plane
Modern microservices
Email server components
Component
Examples
Role
MTA
Postfix, Exim, Microsoft Exchange
Mail Transfer Agent
MDA
Dovecot
Mail Delivery Agent
MUA
Outlook, Thunderbird
Mail User Agent
Relay
SES, SendGrid, Postmark
Outbound at scale
Gateway
Proofpoint, Mimecast
Inbound scanning + DLP
DNS records mail needs
Record
Purpose
MX
Mail server for the domain
SPF
Which IPs are allowed to send
DKIM
Cryptographic signature on outbound mail
DMARC
Policy for handling SPF/DKIM failures
PTR
Reverse DNS - many providers require valid PTR
Self-host vs SaaS
Option
Pros
Cons
Self-host
Full control
Full responsibility
Hybrid
SaaS + on-prem relay for archives
Two systems to operate
SaaS
Microsoft 365, Google Workspace
Default for SMEs
Common server pitfalls
nginx + Apache on the same box without distinct ports.
IIS-only TLS without ciphers updated for the year.
Self-host mail without SPF, DKIM, DMARC - all your mail flags as spam.
One mailbox for both alerts and humans; nobody reads it.
Mentor’s tip: nginx is the safe default for web; Postfix + Dovecot for mail if you must self-host. SPF + DKIM + DMARC are non-optional in 2025. Move mail to SaaS unless compliance forbids it.
Discussion
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