Firewall ports needed for proper Zimbra email server operation.

The following TCP ports need to be open in order for Zimbra to work properly:

POP3 - port 110

IMAP - port 143

SMTP - port 25

HTTP - port 80

HTTPS - port 443 

Secure SMTP (SSMTP) - port 465

Secure IMAP (IMAP4-SSL) - port 585

IMAP4 over SSL (IMAPS) - port 993 - NECESSARY FOR iPHONE CONNECTIVITY

Secure POP3 (SSL-POP) - port 995