Within a week of the filing of your petition, the bankruptcy court clerk mails your creditors notice of the filing and the imposition of the automatic stay. Until the creditors get notice, it may be necessary for you supply the creditor with the case number and date of your bankruptcy. Once they have been given notice, they must stop collection efforts against you or they may be liable for court sanctions. Many large creditors subscribe to services that will notify them within seconds of your filing. Thankfully, for the vast majority of people, once their bankruptcy petition is filed, that is the last they hear from their unsecured creditors.