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.
Third-party virus scanners sometimes detect the ClamAV signatures as viruses and move them into quarantine.
Please define exceptions for the following directories in your third-party virus scanner:
C:\Program Files (x86)\Common Files\JAM Software\ClamAVInABox
You can train the Bayes filter with multiple emails at once. To do this create a POP3 account in your Exchange Server (e.g. named trainSpam) and setup an account in SmartPOP2Exchange pulling emails from that account.
Add a rule for this account applying for any message with the action to train the Bayes filter with spam. To use this account for training attach all spam emails as attachments to an empty email and send it to the trainSpam account. SmartPOP2Exchange will detect the empty wrapper message and only trian the attached messages.
The same can be done with a "trainHam" account.
Your Exchange Server returns this error if the sender address is blocked by the sender filter of the Exchange Server: https://docs.microsoft.com/en-us/Exchange/antispam-and-antimalware/antispam-protection/sender-filtering?redirectedfrom=MSDN&view=exchserver-2019
Please deactive this filter or at least exclude SmartPOP2Exchange from ever being rejected.