Turn On IMAP Services

On the windows server where exchange runs, ensure Microsoft Exchange IMAP4 and Microsoft Exchange IMAP4 Backend started and set the mode to automatic.

Setup Firewall / NAT Port Forwarding On The Router

By default IMAP listens to port 143 and 993 (SSL), the idea here is by setting up port forwarding, packets that hits your office IP will be translated and forwarded into the exchange server. There are no generic instruction on how to do this as each router type is different, however conceptually you want to setup a rule to this effect:

When a packet arrives to to port 143 and/or 993, translate it into and forward it to port 143 and/or 993

Keep in mind the Windows server has its own firewall so you might need to open the ports there too

Setup DNS Alias

Typically you would want imap.mycompany.com to point to the Windows server that hosts Exchange. This can be achieved by adding a DNS A Record on your internet domain manager (provided by your domain hosting).

Observe IMAP Settings on Exchange Admin Center (EAC)

Make sure you have it enabled, selected login method to your liking etc:

And Finally Setup IMAP on Your Phone / Email Client

Depending on your setting, the IMAP details might look like this:

• IMAP server: imap.mycompany.com
• Port: 143
• Enable TLS: true
• Username:
• Password: