When you are signed into MemberHub and go inside one of your hubs, you should see Messages in the left hand side (administrators might have turned this feature off if you do not see it). Once on the Messages page, click the blue New Message button on the right.
If the administrator has allowed everyone the ability to create a message, then you will see radio buttons for sending as Announcement or send as Discussion.
Announcements are one-way messages to the entire group. They are designed for short, instant notifications like “Ball game cancelled tonight because of weather.”
An announcement can be received via e-mail or text message on your cell phone (depending on your personal settings). By default announcements marked as urgent are delivered via text message.
Depending on how a hub is configured, an administrator may be the only person in the group who is allowed to post announcements (this is the case by default).
To create an announcemnt, you would simply select your recipients by clicking the blue Select Recipients button. By default, a message is sent to everyone. After that, you would only need to fill in the subject and write in some text. for announcements, the texting option is available and you are able to click the Copy Text from Email Message button to copy the first 140 characters in the email.
Announcements also have expiration dates to them if you would like it to display for a set amount of time.
Discussions are created the same way as announcements, however texting is not an option. They are meant to be more of an email thread where you can share ideas and reply all to messages.
Discussions do not have the option to expire, but you are able to delete them at your will.
One thing that is really unique is that every hub has a customizable email address. Sending an email to that address will automatically create a new discussion and record the thread in the hub. To discover the discussion board e-mail address for a particular hub, look in the sidebar of the discussion board. If you are the hub administrator, you can customize the e-mail address on the General tab of Hub Settings. You can also create and read discussions in hub on the Discussions page.
As noted in one of screenshots, Messages also allow the ability to save draft just like in your email client. You can save the draft by clicking on the blue Save Draft button at the bottom of the message.