You will have received an email similar to below informing you that your email is encrypted by Unipass Mailock.
When you click on the "Read my message" tab, you will be taken to a page asking you to verify your email address.
Once you have verified your email address, the page will ask you to enter a verification code which is sent to your email inbox. Please open your emails and find the code.
Once the code has been entered successfully, you might be asked to answer challenge question. If successfully answered your email will then be opened.
You now have the option to reply to the sender by clicking on the reply tab at the top right of the screen.