Configuration Errors
- Error 530-5.7.0: Must issue a STARTTLS command first
- Error 454-5.5.1: STARTTLS May Not be Repeated
- Error 554-5.7.0: Too Many Unauthenticated Commands
- Error 512: Domain Can Not Be Found
- Error 546: Email looping
- Error 515: Destination Mailbox Address Invalid
- Error 501-5.5.2: Cannot Decode Response
- Error 400: Invalid_request
- Error: SMTP Error 555
- Error: SMTP Error 538
- Error: SMTP Error 511
- Error 405: Method Not Allowed
- Error 504: Command Parameter Not Implemented
- Error 502: Command Not Implemented
- Error 501: Syntax Error in Parameters or Arguments
- Error 553: Requested Action Not Taken
- Error 500: Syntax Error, Command Unrecognized
- Error 455: Server Unable To Accommodate the Parameters
- Error: The From Address Does Not Match a Verified Sender Identity
- Error: AADSTS50011: The Redirect URI Does Not Match
- Error: Invalid_request: AADSTS50194
- Error: Signature Does Not Match
- Error: Redirect URI Mismatch
- Error: API_key: Invalid
- Error: Invalid Client Secret
- Error: Channel Not Found
- Error: MailboxNotEnabledForRESTAPI