This may be trivial but I can't figure out why some emails aren't working for my process.
I'm running the command line script from a batch file with about 200 individual executions - each passing a crystal report .pdf to a seperate recipient.
Some instances work successfully and others don't.
The email server I'm referencing is a relay for MS365 <clientsdomain>-com.mail.protection.outlook.com:25 (no authentication)
Issue started after the relay...
Does the message below mean the recipient requires higher security/whitelisting?
See error log example:
2021-02-11 12:20:04 Error Send e-mail with subject "Transmission Detail for XYZ COMPANY - Wednesday": E-mail message send failed: IOException occurred during SSL negotiation. InnerException message follows: Authentication failed because the remote party has closed the transport stream.: Authentication failed because the remote party has closed the transport stream.