Early 2000's was also when email got encryption between a mail client and the server. Belligerent sysadmins may try to block all ports except 80 and 443, but us

Early 2000's was also when email got encryption between a mail client and the server. Belligerent sysadmins may try to block all ports except 80 and 443, but users get a bit upset when 143, 993, 25 or 465 get blocked and mail stop working.