This method will guide you to create an Outlook rule to automatically copy emails to another folder by the specified subject keywords in Outlook. Please do as follows:

1. Select the mail folder you will create the rule for, and click Home > Rules > Manage Rules & Alerts. See screenshot:

2. In the Rules and Alerts dialog box, please click the New Rule button. See screenshot:

3. In the Rules Wizard, please click to highlight the Apply rule on messages I receive option, and click the Next button. See screenshot:

4. In the Rules Wizard (which condition(s) do you want to check?), please set the filter criteria as you need.
In my case, I need to copy all emails whose subjects contain the keyword of comment. Therefore, I will configure as follows:
(1) check the with specific words in the subject option,
(2) click the linked text of specific words in the Step 2 section;
(3) add the keyword comment in the Search Text dialog box and click the OK button;
(4) click the Next button in the wizard. See screenshot:

5. In the Rules Wizard (what do you want to do with the message?), please do as below screenshot shown:
(1) Check the move a copy to the specified folder option;
(2) Click the linked text of specified in the Step 2 section;
(3) In the Rules and Alerts dialog box, specify the folder you will copy emails to, and click the OK button;
(4) Click the Next button in the wizard.

6. Click the Next button in the Rules Wizard (Are there any exceptions?) directly.

7. In the last Rules Wizard, please:
(1) Name the new rule in the Step 1 box;
(2) Check options as you need in the Step 2 section;
(3) Click the Finish button.

Now all emails whose subjects contain the keyword of comment are copied to the specified folder.

8. Close the Rules and Alerts dialog box.

Batch save multiple emails to hard disk as text/PDF/HTML/CSV files in Outlook

Normally we can export/save an email message as a text file with the Save As feature in Outlook. But, for batch saving/exporting multiple emails to individual text files, you have to manually handle each message one by one. Time-consuming! Tedious! Now, Kutools for Outlook's Bulk Save feature can help you quickly save multiple email messages to individual text files, PDF files, HTML files, etc. with only one click!

Set a rule where my name is not in To or Cc field in Outlook

Set rule if subject does not contain certain words in Outlook

Restore missing Run a script option in Outlook rule