Hello,
Since early this week our e-mail accounts at zoho are suddenly returning back the messages to the senders with the following error:
- SMTP error from remote mail server after RCPT TO:<########@tres60.co>:
host tres60.co [192.185.108.244]: 550-Please turn on SMTP Authentication in your mail client, or login to the
550-IMAP/POP3 server before sending your message. out2.sf2.colhost.com
550-[190.8.179.125]:53258 is not permitted to relay through this server without
550 authentication.
At first we thougth it was the other side (sender) issue but then from different domains, different ip addresses, different email providers the messages didn't reach our mailbox and every person who received the bounce back got the same error.
We performed the test using e-mails at gmail via web and got the same error in the bounce back message.
This it's been happening in different timeframes during the last days and we need your help and attention to help us identifying the issue since it seems to be something internal at zoho.
Regards,
Germán