Problems receiving email when to and from are from the same domain

Hi! I have problems with my contact forms when the “from” and the “to” are from the same domain. The server where the web is hosted is from the own client.

In this case, is a informative email. The sender is [email protected], and the “to” is [email protected].

[email protected] never gets the email. If I change the “to”, for example, [email protected], I get the email perfectly.

Is like the server thinks is spam, and doesn’t send the email? I don’t know, I’m really desperate, I am a web designer, not a developer, so I really don’t understand what’s happening. could you help me?? any alternative??