The error 0x80040607 is prominently noticed in Outlook 2007 and Outlook 2010. In these versions, an error “Send test e-mail message: An unknown error occurred, error code: 0x80040607” sometimes appears while sending or receiving emails.
Improper POP3 and SMTP configurations are known to be the reasons for the Outlook error 0x80040607. If the SMTP is not configured correctly or you have not entered correct port numbers, it leads to error 0x80040607 while sending your emails. If SMTP authentication is not enabled, then also, this error can occur.
You can fix the error 0x80040607 by changing the SMTP authentication settings in Outlook. This is how you can change the SMTP authentication settings:
Outlook errors can be caused by damaged and corrupted PST files. You can resolve these issues by repairing your damaged PST files. You have two options available to repair your damaged PST files - Inbox Repair tool or a third-party tool. If you choose Inbox Repair tool, it can only repair those files whose size is less than 2GB. So, if you have files larger than 2GB, then you have to use a third-party tool like Kernel for Outlook PST Repair. It has some prominent feature like: