title: AWS Cognito verification email not received by user account
body: <p>While creating user in userpool, user invitation messages are sent with a temporary password but email verification messages is not being sent.<br/>
  I was creating a very simple setup to try out aws cognito service.
  Here is what I did in AWS cognito, I created a user pool with step by step as follows:<br/>
  1)What do you want to name your user pool?<br/>
  -> testpool<br/><br/>
  2)How do you want to create your user pool?<br/>
  -> step through settings<br/><br/>
  3)How do you want your end users to sign in?<br/>
  ->Email address or phone number-Allow email addresses<br/><br/>
  4)What password strength do you want to require?<br/>
  ->Minimum length=6<br/><br/>
  5)Do you want to allow users to sign themselves up?<br/>
  ->Allow users to sign themselves up<br/><br/>
  6)How quickly should user accounts created by administrators expire if not used?<br/>
  ->Days to expire-7<br/><br/>
  7)Do you want to enable Multi-Factor Authentication (MFA)?<br/>
  ->off<br/><br/>
  8)Do you want to require verification of emails or phone numbers?<br/>
  ->Email<br/><br/>
  9)You must provide a role to allow Amazon Cognito to send SMS messages<br/>
  ->testpool-SMS-Role<br/><br/>
  10)Do you want to customize your email verification messages?<br/>
  ->Verification type-link<br/>
  ->Email subject = Your verification link<br/>
  ->Email message = Please click the link below to verify your email address. {##Verify Email##}<br/><br/>
  11)Do you want to customize your user invitation messages?<br/>
  ->SMS message = Your username is {username} and temporary password is ->{####}. <br/>
  ->Email subject = Your temporary password<br/>
  ->Email message = Your username is {username} and temporary password is {####}. <br/><br/>
  12)Do you want to customize your email address?<br/>
  ->no<br/><br/>
  13)Do you want to add tags for this user pool?<br/>
  ->no<br/><br/>
  14)Do you want to remember your user's devices?<br/>
  ->no<br/><br/>
  15)Which app clients will have access to this user pool?<br/>
  ->none(will simulate from create user option in genral setting-user and group)<br/><br/>
  16)Do you want to customize workflows with triggers?<br/>
  ->no<br/><br/>
  17)Review page - this page shows summary of whatever I selected
  <strong>Create pool</strong><br/><br/></p>
  
  <p>Now after pool creation went ot genral setting-user and group and clicked <strong>create user</strong>
  A Create user pop-up shows:<br/>
  Username (Required): myEmailAddress<br/>
  Send an invitation to this new user?: check<br/>
  Temporary password: left blank<br/>
  Phone Number: empty(not required)<br/>
  Mark phone number as verified? unCheck <br/>
  Email: myEmailAddress <br/>
  Mark email as verified? unCheck <br/>
  Click on Create User<br/>
  <br/>
  A mail is received into my account form no-reply@verificationemail.com via amazonses.com,<br/>with subject: Your temporary password<br/> with message as: Your username is somemailid@gmail.com and temporary password is agsjyk.
  <br/>This is okay.</p>
  
  <p>But I didnot receive any verification mail link before previous mail.</p>