Correos

the problem is that the emails you send to subscribers sometimes send them as https and they can not open them since you have to send them as http

if in the example emails this is the email that you send https://ganaderiasos.com/2018/07/28/implementacion-del-conocimiento-y-la-experiencia-israelies-para-enfriar-a-las-vacas-en -the-world / and should be
http://ganaderiasos.com/2018/07/28/implementacion-del-conocimiento-y-la-experiencia-israelies-para-enfriar-a-las-vacas-en-el -world/