<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2010-06-23</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000897893</issuerCik>
        <issuerName>PEERLESS SYSTEMS CORP</issuerName>
        <issuerTradingSymbol>PRLS</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001011938</rptOwnerCik>
            <rptOwnerName>BATHGATE STEVEN MARK</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O PEERLESS SYSTEMS CORPORATION</rptOwnerStreet1>
            <rptOwnerStreet2>2361 ROSECRANS AVE</rptOwnerStreet2>
            <rptOwnerCity>EL SEGUNDO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>90254</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common stock</value>
            </securityTitle>
            <transactionDate>
                <value>2010-06-23</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>10000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>447481</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Options to acquire common stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>2.77</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2010-06-23</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>10000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F5"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <value>2020-06-23</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>10000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>10000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Includes 10,000 shares of restricted stock issued to Mr. Bathgate upon his re-election to the Board at the 2010 annual meeting of stockholders. 5,000 of these shares will vest on the earlier of June 23, 2011 and the date of the 2011 annual meeting of stockholders, and the remaining 5,000 shares will vest on the earlier of June 23, 2012 and the date of the 2012 annual meeting of stockholders.</footnote>
        <footnote id="F2">Also includes 300,000 shares held by Mr. Bathgate's wife, 40,000 shares held by Bathgate Family Partnership Ltd., and 43,000 shares held by Mr. Bathgate's adult children residing with him.  Mr. Bathgate disclaims beneficial ownership of these shares.</footnote>
        <footnote id="F3">All shares were received in consideration for Mr. Bathgate's service as a director of the Company.</footnote>
        <footnote id="F4">Twenty-five percent (25%) of the shares subject to such option shall vest and become exercisable on June 23, 2011 (the completion of one year of service measured from the grant date). The balance of the shares subject to such option shall vest and become exercisable in a series of thirty-six (36) successive equal monthly installments upon completion of each additional month of service until all of the options are vested.</footnote>
        <footnote id="F5">All options were received in consideration for Mr. Bathgate's service as a director of the Company.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Steven Bathgate</signatureName>
        <signatureDate>2010-06-23</signatureDate>
    </ownerSignature>
</ownershipDocument>
