VERIFIED SOLUTION i
Processing of DIJ files, fails with message 'smtp.SMTPSendFailedException: 452 4.3.1 Out of memory' in EngageOne Deliver application logs.
This message is thrown by SMTP server when experiencing memory problem.
ResolutionUPDATED: January 29, 2019
Ensure mail server is not experiencing memory problem. Restart of SMTP Service may also help as it will bring down the memory usage of same.