Yes, you can. The offline messages are kept for delivery for 10 days. After that they will be considered expired and deleted from the messages queue.
No, you can’t communicate with users that are not in your contact list.
Co-Browse (collaborative web browser) is a feature that allows you to “share a browser” with another user. You navigate the browser to a web page and the other user’s co-browser will be navigated to the same page. For more details check Co-Browse in the Features section.
With Whiteboard you can draw diagrams, schemes etc and this way to share your ideas visually. You can choose different shapes, colors, tools. For more details check Whiteboard in the Features section.
If you drag-and-drop the file in the conference window or choose “Send File” button from the same window, all the users that are in the conference will receive it. If you want to send the file only to one user, you can select the name from your contact list and then click on “Send File” button from the main window. You can also drag the file onto a user name in your contacts list.
The Receive File Dialog shows the folder where the files will be saved. If you want to store the file in a different place just click the “Save As” button. After the Receiving File has completed, you can click on the “Locate” button and the folder containing the received file will be open.