If you want to unblock a gmail sender using the android app, then follow the steps below:

How to unblock email from gmail. In the gmail settings menu, head over to the “filters and blocked addresses” category and check the email addresses that you want to unblock, as shown here. Launch the gmail android app. Select the contact’s email address from the list that you want to unblock.

After you open the email. Next to the sender's name, click unsubscribe or change preferences. Select see all settings menu.

Click the gear icon and open settings. Learn more about the new layout. After you have successfully logged in, find and open the email conversation or message that bothers you which you want to block.

To apply the setting to everyone, leave the top organizational unit selected. Stay on top of everything that's important with gmail's new interface. Find a message from the sender you want to be.

Here are the steps for blocking that sender’s email address: On your computer, go to gmail. You can also select all by clicking the link if you don’t want to unblock everyone currently on the list.

In the section under the heading the following email. Learn more about the new layout. Go to ‘filters and blocked addresses’.