I have a workflow that reconciles time submitted on timesheets with vacation data from our payroll system and emails everyone who did not submit enough total time between the two of them during a given week.
This process has run for 2+ years including last Monday and today failed with the message:
ERROR Send Email 3:34 Execute failed: Error while communicating with the smtp server: com.sun.mail.smtp.SMTPSendFailedException: 550 5.7.607 Access denied, banned sending IP [my companies main domain]. To request removal from this list please visit https://sender.office.com/ and follow the directions. For more information please go to Remove yourself from the blocked senders list and address 5.7.511 Access denied errors - Office 365 | Microsoft Learn AS(1435) [DM6NAM10FT042.eop-nam10.prod.protection.outlook.com]
Note that “com.sun.mail.smtp” is NOT the SMTP server that I configured and am using in my workflow nodes.
Is this used by Knime under the hood?
Any advice on what is going on and why this might have started this week after 2+years of no issues.
My list of users that needed to receive email notifications had only 15 members. On the first run it send the email to 7 members. When I reran the process for the remaining members, it send out 3 emails and then again failed with the same spam/phishing error from Office 355.
My organization uses the same SMTP Server for other email notifications and never had issues.
It seems my email or domain is now listed as a SPAM site in Microsoft Office 365. I followed the instructions and link and could not be delisted. I had to click on an escalation request.
I am still able so send emails from the same FROM email from my personal outlook account and via Knime on the VM that I use.