IKANO will work with you to make the migration as smooth as possible. We have experience assisting numerous types of companies into Google Apps Partner Edition. Below is a normal migration scenario.
Company will be supplied by IKANO a Google Apps for ISP's contract. Please call us if you need a quote as custom quotes are available. Company executes signed Google Apps contract and faxes it back to 1866-627-8808 or scans and emails it to email@example.com.
IKANO sets up the requested domain(s) on Google Apps for ISP's and provides the Company administrative access to the Google Apps control panel.
Within 14 days, Customer needs to complete the verification process in the control panel of each domain name.
Company will begin to communicate upcoming change to customers.
Customer will bulk import email usernames, password, first and last names into Google system. Plain text passwords (minimum of 8 characters in length) are necessary to bulk import the users into the Google system. When you bulk import users using Google's tool in the control panel, the system will automatically enable POP3 for all of the customers so they do not have to login to the webmail system and enable that setting. Creating the users on Google also will trigger the billing on IKANO's side.
IMAP migration is completed and Address book migration is completed. In order to perform the IMAP migration, you will need the IMAP server name and a list of the usernames and passwords that are on your old email system. CSV file, 1 user per line. More info on this is available upon request.
Dual delivery (email routing) is enabled and MX records are pointed to Google, this allows customers to use your old email system and the new email system for a period of time.
Company communicates with subscribers to change to Google Apps. Webmail access is preferred.
Company works with subscribers still connecting to old mail servers. Communicates changes for POP3 settings.
Retirement of old mail server and the Customer disables dual delivery.
Example Target Launch Schedule: Target Launch Date [May 1]
Apr 1 - Company communicates to customers upcoming changes and enforces 8 character passwords for migration.
Apr 25 - Company to get together a list of all usernames and passwords (8 character minimum) for bulk import into Google system. Customer can perform bulk import in the control panel.
Apr 31 - Company performs IMAP migration of folders and email sitting on your old mail server into Google system. Address book migration should happen right now as well. Your current servers will need to work with IMAP to do this. You will need to have a plain text list of usernames and passwords. Google Also has a Email migration API that can be used if you do not have plain text passwords: https://developers.google.com/google-apps/email-migration/
May 1 - All email migrated to Google. Customers can now use new platform.
May 1 - Company changes MX records to Google and enables Dual delivery so both the old email system and Google.s mail system can be used at the same time. Explanation of Dual Delivery: When you are ready to go live on Google, we have an easy way to be able to process mail on both the Google system and your old system at the same time. Users will continue to receive mail on their old system and new system during this period. This means that your users can have a 30 or 60 day window for example to move from your old mail system to the new email system. This will mean that your migration can be spread out over a period of time and does not all have to occur in one day.
May 2 - Company communicates with customers about the new webmail system URL and new POP3 settings to customers who are still connecting to old server and did not make the change.
Jun 30 - Planned retirement of old mail system.
Managing Your Email Users (2 options):
You can use the web based interface at www.google.com/a/yourdomain.com to manage your subscribers. This is the default Google admin interface and will be available after your domain name(s) are setup.
Google has API's that will let you programmatically interact with Google directly to add, modify, delete subscribers and also provide reporting features. Google API and Single Sign on Info is here: http://developers.google.com/a/google-apps/ or you can use something like Flash Panel, which you seem to be pretty confident in.