One source which may cause this problem are the ClamAV mirror servers. To solve the problem, please delete the following file:
Another problem might be caused by the Windows Defender. Add the following paths to the exclusions:C:\ProgramData\JAM Software\ClamAVInABox\SignaturesC:\Program Files (x86)\Common Files\JAMSoftware\ClamAVInABox\sanesecuritydbtemp
This error message is caused by your Exchange Server and no problem of SmartPOP2Exchange.
Your Exchange Server also includes a simple spam filter module called imf. This one refuses messages detected as spam by default.
Because of this SmartPOP2Exchange saves the email and creates that notification message which is send to the user instead to avoid mail loss.
To solve the problem you need to change the behavior of the Exchange Server and make it accept any message from SmartPOP2Exchange.
You either should disable the content filter and sender filter of your Exchange Server or at least change the action to quarantine instead of refusing.
Please configure your Exchange Server to accept any message from SmartPOP2Exchange. Please note that messages in your POP3/IMAP account already count as finally delivered and because of this the behavior of refusing messages by the Exchange Server is similar to their deletion. If that is your intention we recommend you configure your Exchange Server to delete the messages or move them into quarantine. This avoids the error messages in the log of SmartPOP2Exchange and multiple delivery attempts.
Many spam emails contain syntactically invalid email addresses in the from field. Since most SMTP servers (including Exchange Server) refuse messages with invalid from addresses SmartPOP2Exchange gives a warning when it detects such an invalid address.
With SmartPOP2Exchange V7.2 detected invalid sender addresses are automatically replaced with "email@example.com".
For older versions you may create a global rule like this: Condition: "Messages with an invalid sender address" --> Action: "Replace sender address with 'firstname.lastname@example.org'".
Under certain circumstances a third-party virus scanner might prevent SmartPOP2Exchange from accessing the settings files. This results in SmartPOP2Exchange creating a new default settings file.
SmartPOP2Exchange regularly creates backups of the current settings. If your config file has not yet been overwritten it can easily be restored.
To prevent this add the folder which contains the config file (C:\ProgramData\Jam Software\SmartPOP2Exchange) to the exception list of the software that caused the problem. This is also the folder in which the backups are stored.