The email rocio.nieto@channnelplanet.com is not letting send emails out.

The email rocio.nieto@channnelplanet.com is not letting send emails out.

Hello

We have an email account named rocio.nieto@channelplanet.com that is not letting send emails to customers.. The email setup is ok and has sufficient space to work.  The other emails accounts are working ok.

Thank you 

Juan Pablo Barcenas