Why are links removed from emails?

Question

Django

I send emails from a site on Django:

'Пройдите по этой ссылке чтобы восстановить пароль 
<p><a target="_blank" href="%s/auth/password-recovery/%s">Восстановить</a></p>' % (site, link)

And when they arrive, the attributes are removed , in Yandex href, and in gmail it generally remains naked