I've never had a PST quarantined, so I can't help you on that. However, I do suggest that you use MAILWASHER spam control software, it will give you at least a fighting chance in the future.
I'm using an older version, for now, just fine with Windows 8.1U (works fine on Windows 7). Not only does the program provide you a list of your e-mails on the server, and you can mark the ones you want to delete, it allows to place filters that can automatically delete unwanted e-mails, flag e-mails, etc. It includes white lists and blacklists, even using wild cards. For instance on my installation, I've have all top level domains (e.g. *.IE, *.RU, *.UA, etc) marked to be deleted, except for (*@*.ca, *@*.com, *@*.gov, *.mil, *@*.org, *@*.us). As indicated, you can also create filters to take action. For instance (actual filter):
THIS FILTER IS ENABLED AND TAKES PRECEDENCE OVER FRIENDS LIST, IF BODY CONTAINS BIT.LY OR TINYURL, MARK THE E-MAIL TO BE DELETED.
FILTERS ARE CREATED VIA A WIZARD. The above will mark any e-mails with the indicated URL shorters in the body, even if the email was received from someone on the friend's list for deletion. Then when you press "Process", it connects to your e-mail server, deletes the e-mails you tell it to, opens Outlook, so then you can send/receive your e-mails.
Note, to be really effective, your outlook should be:
1. Set to manual send/receive.
2. No timed, automatic send and receive.
3. No auto checking on startup or shutdown.
4. Before you send an e-mail (clicking send/receive), always start MAILWASHER, and check the e-mail on the server first, mark messages appropriately, and "process" the messages. Then use send/receive in Outlook.
Some might find the extra step in using MAILWASHER when sending/receiving e-mails a pain. But once the person gets use to it, they will find it a GREAT benefit.
I've looked at other SPAM control software, and of all the ones I looked at, all of them, except MAILWASHER, does their action ONCE THE E-MAILS ARE DOWNLOADED, WHEREAS MAILWASHER DOES IT BEFORE THE E-MAILS ARE DOWNLOADED.
The key is that you see what's on your e-mail server BEFORE it gets to your computer, and will reduce, or almost eliminate SPAM, and increases the probability that you won't be infected as easily (MAILWASHER IS NOT ANTI-MALWARE/ANTIVIRUS SOFTWARE).
I've been using it for quite some time, and it helps alot.
Best of luck!