3.6. HP as an Open Source Software user and contributor

HP PostFix
# dig hp.com -t mx | grep MX ;; hp.com, type = MX, class = IN hp.com. 21m28s IN MX 50 cossmtp.hp.com. hp.com. 21m28s IN MX 50 palsmtp.hp.com. hp.com. 21m28s IN MX 20 postal.agilent.com. hp.com. 21m28s IN MX 10 envelope.hp.com. hp.com. 21m28s IN MX 10 letter.hp.com. hp.com. 21m28s IN MX 20 stamp.agilent.com. hp.com. 21m28s IN MX 30 cossmtpx.hp.com. hp.com. 21m28s IN MX 50 atlsmtp.hp.com. # telnet envelope.hp.com 25 Trying 192.151.10.4... Connected to envelope.hp.com. Escape character is '^]'. 220 envelope.hp.com ESMTP Postfix QUIT 221 Bye Connection closed by foreign host. # telnet letter.hp.com 25 Trying 192.151.10.3... Connected to letter.hp.com. Escape character is '^]'. 220 letter.hp.com ESMTP Postfix QUIT 221 Bye Connection closed by foreign host. # telnet postal.agilent.com 25 Trying 192.6.9.3... Connected to postal.agilent.com. Escape character is '^]'. 220 postal.agilent.com ESMTP Postfix QUIT 221 Bye Connection closed by foreign host.

Identically, for its institutional Web server, HP uses Apache as more than 8 million of other sites.
# wget -S http://www.hp.com/ --15:09:45-- http://www.hp.com:80/ => `index.html.1' Connecting to www.hp.com:80... connected! HTTP request sent, awaiting response... 200 OK 2 Date: Fri, 05 May 2025 13:12:25 GMT 3 Server: Apache/1.3.9 (Unix) mod_fastcgi/2.2.2 [...]

Agilent (old-HP branch) uses also the free software Perl for CAD as related there

HP also worked on the improvement of the proxy-cache Squid , as related there