Problems with receiver not getting their e-mail

Question

Hi, i have just gotten this new e-mail, and i am having problems with it.

When i send an email, it says it is sent in my account. But when i as the person receiving the e-mail if they have gotten i they can't find it anywhere. They have looked in their trash folder and everywhere else but it doesn't appear anywhere. Is there anything i can do to change this. I need my e-mail to work for my student group.

Thank you for any answers!

Best regards