SharePoint 2013 Online » Emails » Iinternal emails not received by recipent

Hello,

Here is my scenario:

I've created an workflow that sends emails (Created in SharePoint Designed, for SharePoint 2013 as a SharePoint 2010 Workflow). This workflow was add to the "On new item" event.

This workflow was working, but for some reason some emails stop beeing send.

The emails that are send to accounts like gmail or similar are received, but if i use as recepient an Office365 account the emails are not delivered.

What I have done so far:

Created a new and simpler SharePoint 2010 workflow. Does not Work

Created a new and simpler SharePoint 2013 Workflow. Does not work;

Created a new workflow in another list. Does not Work;

Created an alert in one list. Does not Work;

Any thoughts in what it can be?

Thanks.

Mário Encarnação