Take below the basic following steps:
1. If you can not find the verification email, check your spam mailbox or click [Send verification email] button again in General Settings.
2. At the last email you received, you must verify your email address. If you resend the email, all of the confirmation links in the old emails will expire.
3. Sign out and sign in to Sendy again. Even though your account has already been confirmed, a temporary error can cause the message that you didn't complete email confirmation to be displayed incorrectly.