If you need to update people on one or more of your lists you can get a comma separated list of emails and use your own email client to send them.
Go to the Email Addresses Page
Here are the two ways to get your list of emails.
From the Home Page
On the home page click Export > Get Email Addresses
From a List
While viewing your list, Click on the Email button
Getting Emails
Once on the Email Addresses page, you can select which lists you want to include and what you want to separate them by. “Comma” is supported by most email clients.
Then click Get Emails. The result will be a long string of text which you can copy and then paste into the To line in your email client.