Error sending email to my disroot

Hi there! the last few days I’m receiving an error message while send an email from a certain mail address to my disroot email. This is the error message:

Sender address rejected: Need to login (in reply to
RCPT TO command)

Diagnostic-Code: smtp; 554 5.7.1 user@domain: Sender address
rejected: Need to login

Anyway I still receive the message but the sender receives the error above. Also the the automatic forwarding of any messages that I have set doesn’t work. I encounter this error only when the sender belongs to a specific server. This server have had a troubled upgrade in the last days that probably is part of the problem. Any idea on how can I solve this? I can send more details if needed. Thanks a lot. R

It looks like it could be an issue with the other service provider. Perhaps you want to send message to so we can more freely share more details and follow up on this.

Sure. I just sent an email. Thanks