I was able to change incorrect grammar in out-going email confirmation text with the following:
Find: Easy Coming Soon, click Edit, this will take you to Edit Plugins page.
Find: Plugins File, far right column.
Find & click on: easy-coming-soon/template/coming_soon_display.php
Code for this file will appear in Edit Plugins window on left.
Scroll almost to bottom & find following:
$to1 = $email;
$subject1 = "Coming soon page";
$message1 = "Thank you for subscribing. We will notify you soon.";
$from1 = $notification_settings['email_address'];
$headers1 = "From:" . $from1;
Change text to your preference as I did & click red Update File button at bottom. This should do it, check with a test email.