Cannot receive email from one sender

More information, please:

Does the sender get any sort of error indication? Do you?

Can the sender reach other recipients in your domain?

Can you receive email from other users in the sender's domain?

Do you have another email address (preferably at a different domain) where you can try receiving these messages?

Have you checked your junk mailbox?

Do you have any mail handling rules active on your domain's server or on another device?