# Architecture

ApisCP uses a variety of services managed directly by ApisCP with minimal configuration. The diagram and table summarize components and relevant documentation for each segment.

ApisCP platform diagram

Service Group Service Role
Apache UI
apnscpd Privileged communication
Horizon Job runner
Proxy Frontend panel proxy (optional)
Redis Temporary storage
BoxFS (filesystem)
OverlayFS Account segregation and copy-up
haproxy SSL/TLS termination
Dovecot IMAP/POP3
Postfix SMTP
PostSRSd Sender-rewriting scheme
Pigeonhole IMAP sieve language
rspamd Spam filter, policy milter, DKIM (optional)
SpamAssassin Spam filter (optional)
Redis Temporary storage for rspamd
Maildrop Local delivery agent
Authlib LDA delivery translation
Majordomo Mailing lists
Apache (HTTP)
Apache HTTP server, high-performance configuration
PHP-FPM PHP service workers
Passenger Polyglottal language launcher
Pagespeed HTML rendering optimizer
mod_cache Output cache
Web application firewall
Evasive Brute-force protection
Fortification Privilege separation framework
ModSec Malware protection
ClamAV Malware scanner
Rampart Threat deterrent, firewall
Resource enforcement
cgroups Per-account resource limitations
TimescaleDB Long-term server + account statistics
Argos (monitoring)
Monit Service monitoring
ntfy Defect alerts
MySQL Panel frontend data, web apps
OpenSSH SSH server
PostgreSQL Account metadata, mail routing, statistics storage
rsyslog Logging
vsftpd FTP server