If someone is annoying you you can use the custom filter settings to block incoming messages and mails.

Despite several measures, strict regulations, and self-imposed privacy, spam SMSs continue to float around. When you are at a meeting or conference you might not want any messages or you might just want to save yourself from general annoyance from friends. The BlackBerry 7 OS helpfully has an integrated firewall that can block unwanted SMSs and even emails from reaching the phone's inbox.

The firewall feature in the BlackBerry 7 OS will let you block incoming messages, BBM pings and even emails. Just follow these steps:
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Step 1:

In the Options App, scroll and choose the Security option from the list.

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Step 2:

From the Security menu option, choose the Firewall setting.

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Step 3:

This will take you to the filter settings to block incoming messages based on numbers, PIN, personal email and enterprise email. You can check the boxes for relevant messages, PINs and emails to block.

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Step 4:

You can also add the exceptions - numbers, PINs or email addresses from which you wish to continue receiving messages.