Gmail SMTP error - Temporary block?
<p>I am using Gmail servers to send email from my system, with a program.
Recently I started getting errors like this:  </p>

<blockquote>
  <p>Data command failed: 421 4.7.0 Temporary System Problem.  Try again later (WS). 6sm3756432pab.11 - gsmtp</p>
</blockquote>

<p>The reasons are given in <a href="https://support.google.com/a/answer/3726730?hl=en" rel="noreferrer">the support</a>.</p>

<p>Can anybody tell me what is the number of emails that can trigger this issue? </p>

<p>Or is it because of some other reasons?</p>