When you write an email, one of the common things is to add attachments which can be a file, picture or another email. Please see the steps below for details:
Step 1: Click "New Email" from the Home tab;
Step 2: Open the folder having the files you want to attach and copy the files;
Step 3: Click anywhere in the new email content area, and paste with the shortcut: "ctrl+v" (or right click then click paste).
Step 4: The files are attached to the email.
Alternatively, please use the traditional method to attach all files with the steps below:
Step 5: Click "Attach File" from "Insert" tab (or from "Message" tab);
Step 6: From the drop-down list, click "Browse This PC…" at the bottom;
Step 7: Browse the path and insert the file by holding down the "Ctrl" key and selecting all the attachments (or repeat the steps to attach one by one);
Step 8: The files are attached.