Steps to replicate the issue (include links if applicable):

• 1. A user attempts to send me an email via the "Email this user" (In Itallian: "Invia un'email a questo utente") link on my user page.
• 2. I receive a notification on Wikipedia that an email has been sent to me, but sometimes the email never arrives in my personal email inbox.

Also:

• 1. I send an email to another user via the "Email this user" link.
• 2. I check the box to request a copy of the message.
• 3. Sometimes I do not receive the copy of the message in my inbox.

Also:

• 1. I do not receive any replies from the recipient of my email.

What happens?:

The email functionality is not working correctly for my account. I am unable to receive all emails sent by other users, and I do not receive all copies of the emails I send or their replies. Sometimes the system indicates that the emails have been sent, but they never arrive in my inbox.

What should have happened instead?:

Emails sent to me from other users should always arrive in my inbox.

Also:
When I request a copy of a sent message, I should always receive that copy.

Also:
I should receive any replies.

Software version (on Special:Version page; skip for WMF-hosted wikis like Wikipedia):

N/A (WMF-hosted wiki, specifically Italian Wikipedia)

Other information (browser name/version, screenshots, etc.):

The issue appears to be with the email system itself, as it affects both incoming and outgoing messages from my account. I have confirmed that my email address is correct in my preferences and have checked my spam folder.