A、It needs to charge for its service. B、It needs to view and manage the mails and contacts. C、It needs the user to click "unsubs

If one of your goals in 2017 is an emptier email inbox, we know a way to help. There is a simple way to end subscriptions to email lists that can send multiple messages every day. Unwanted emails from these sources can fill your inbox quickly and waste your time. But there are tools available to block such mail forever.
[19-1] Unsubscribe Link—You can simply unsubscribe from emails by clicking the “unsubscribe” link. Many emails come with this link at the bottom of the message. Often it is difficult to find. It might be hidden in small print or a light color.
[19-2] Unroll.me—It is a free website that lets users unsubscribe from email lists easily. Sign up for an account and link your email address. [20] You will need to give Unroll.me permission to view and manage your emails and your contacts. Unroll.me will find subscription emails in your inbox and list them at their website. You can click which ones you no longer wish to receive and unsubscribe from them.
[19-3] Gmail Unsubscribe—[21] Google has added a feature to Gmail to make unsubscribing easier. Now, instead of having to hunt for the Unsubscribe link, you can find it at the top of Gmail messages. When Gmail finds an Unsubscribe link in an email message, it adds the link to the top of the message so you can find it more easily. Click on Unsubscribe and a confirmation message will appear. Confirm that you want to unsubscribe.You will then be taken to the Unsubscribe page of the sender or receive a notice from Gmail that you should be unsubscribed.
[19-4] Mail App on iPhone and iPad—The operating system for iPhone and iPad, iOS 10, has added a feature to the Mail app that makes unsubscribing from email lists easier. When the Mail app finds an email message from a subscription service, the message will show a notice that says, “This message is from a mailing list.” An unsubscribe link will be added to the top of the email message. [22] Tap unsubscribe to remove your email address from the subscription list. You can also tap the “X” on the right side of the notification to remove it.
Questions 19 to 22 are based on the recording you have just heard.
19.Which tool is not mentioned in this recording to block unwanted emails?
20.What does Unroll.me need to block unsubscribed emails?
21.What is the new feature of Gmail to make unsubscribing easier?
22.How to remove the email address from the subscription list on Mail app?