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                                                                   EXHIBIT 10.28

                             SECURED PROMISSORY NOTE

U.S. $100,000                                          San Francisco, California

                                January 18, 2000

        FOR VALUE RECEIVED, the undersigned, Mark Rubash an individual residing
in California (the "Borrower"), hereby promises to pay to the order of Critical
Path, Inc., a California corporation with mailing address at 320 First Street,
San Francisco, CA 94105, or its successors or assigns (the "Lender"), the
principal sum of One Hundred Thousand Dollars ($100,000) together with simple
interest thereon at the rate of six and eight tenths percent (6.8%) per annum
from the date hereof, in such coin or currency of the United States of America
as at the time of payment shall be legal tender. Notwithstanding the foregoing,
interest will accrue and be payable at a per annum rate equal to the lesser of
(i) the aforementioned rate of interest plus three percent (3%) or (ii) the
maximum interest rate allowed by law, on all past-due principal from the due
dates thereof until the obligations of the undersigned with respect to the
payment hereof shall have been discharged in full.

        Principal and interest shall be payable hereunder as follows:

        (i) On the earlier of January 18, 2005 or thirty (30) days following
termination of the Borrower's employment with the Lender, the undersigned shall
pay the Lender the entire outstanding principal amount hereof, together with all
accrued and unpaid interest hereon.

        (ii) Notwithstanding the foregoing, so long as there is then no uncured
default hereunder and no Maturity Event (as hereinafter defined) has occurred,
the original principal amount hereof and all of the then outstanding interest
shall be forgiven on a yearly basis, over a two year period beginning the date
hereof, as a portion of the Borrower's bonus described in the offer letter dated
January 18, 2000 from Lender to Borrower attached hereto as Exhibit A and the
undersigned shall be released and relieved from the obligation to repay such
amount of reduction to the holder hereof accordingly.

        All payments made pursuant hereto, regardless of when made, shall be
first applied to reduce accrued and unpaid interest on the past-due principal
hereof, and any remaining portion of such payments shall then be applied to
reduce the principal hereof. All payments hereunder shall be tendered at the
aforementioned address of the Lender to the attention of the President or at
such other place as the holder hereof may designate in writing from time to
time. This Note may be prepaid in whole or in any part without premium or
penalty. All payments made hereunder shall be made by the undersigned free and
clear of, and without deduction for, any and all present and future taxes,
levies, charges, deductions and withholdings. The undersigned shall pay upon
demand any stamp or other taxes, levies or charges of any jurisdiction with
respect to the execution, delivery, performance and enforcement of this Note.


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        In the event that (a) the undersigned fails to pay when due the
principal hereof or interest hereon as hereinabove provided and such failure has
not been remedied within five (5) days after Lender shall have given the
undersigned notice thereof, or (b) the undersigned shall fail to pay, perform or
otherwise satisfy when due any other obligation or liability to the Lender under
any document or instrument now or hereafter given as security for the payment of
this Note and such failure has not been remedied within five (5) days after the
Lender shall have given the undersigned notice thereof, or (c) the employment of
the undersigned with the Lender shall terminate or cease for any reason, whether
voluntarily or involuntarily and whether with cause or without cause, or (d)
there shall be filed any petition or there shall be taken any action by or
against undersigned under the provisions of any bankruptcy, insolvency or
similar law affecting creditors' rights generally, or (e) the undersigned shall
make an assignment for the benefit of his creditors, or (f) a court or other
competent authority shall appoint (or the undersigned shall consent to the
appointment of) a custodian, receiver, trustee or other person with similar
powers to take control of the undersigned or any material part of his respective
property or assets, then, in any such event (each a "Maturity Event"), at the
option of the holder of this Note, the entire principal amount then outstanding
hereunder and all accrued and unpaid interest hereon shall become immediately
due and payable.

        The indebtedness evidenced by this Note and the obligations created
hereby will be secured by shares of the Lender's common stock purchased pursuant
to the undersigned's option to purchase 475,000 shares of the Lender's common
stock; provided that the value of the shares used to secure the obligations
created hereby shall not exceed the amount outstanding under this Note.

        The undersigned hereby makes the following representations and
warranties to the Lender and acknowledges that the Lender is relying on such
representations in making the loan:

        (i) Borrower shall have good and marketable title to the shares of
common stock issuable upon exercise of the option free and clear of any security
interests, liens or encumbrances.

        (ii) There are no actions, proceedings, claims or disputes pending or,
to the undersigned's knowledge, threatened against or affecting the undersigned.

         This Note may be amended or modified, and provisions hereof may be
waived, only by a written agreement executed by the undersigned and the holder
hereof. No delay or omission by the holder hereof in exercising any of its
rights, remedies, powers or privileges hereunder or at law or in equity and no
course of dealing between the holder hereof and the undersigned or any other
person shall be deemed a waiver by the holder of any such rights, remedies,
powers or privileges, even if such delay or omission is continuous or repeated,
nor shall any single or partial exercise of any right, remedy, power or
privilege preclude any other or further exercise thereof by the holder hereof or
the exercise of any other right, remedy, power or privilege by the holder
hereof. Should this instrument or any part of the indebtedness hereby be
collected by law or through an attorney-at-law, the holder hereof shall, if
permitted by applicable law, be entitled to collect from the undersigned
reasonable attorneys' fees and all other costs of collection. The undersigned
hereby waives presentment, demand, protest and notice of any kind, including
notice of presentment, demand, protest, dishonor and non-payment. This Note
shall be binding upon the undersigned and his respective heirs, legal


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representatives, successors and assigns. The rights and remedies of the holder
hereof described herein and in any documents or instruments delivered as
security for the performance of the undersigned's obligations hereunder shall be
cumulative and not restrictive of any other rights or remedies available under
any other instrument, at law or in equity. This Note and the obligations created
hereby are not assignable by the undersigned.

        In the event that the holder hereof, in enforcing its rights hereunder,
determines that the charges and fees incurred in connection with this Note may
under applicable law cause the interest rate to exceed the maximum rate allowed
by law, then such interest shall be calculated and any excess over the maximum
permitted by said law shall be credited to the then outstanding principal amount
hereof to reduce said balance by the amount of any such excess. It is the intent
of the parties hereto that under no circumstance shall the undersigned be
required to pay, nor shall the holder be entitled to collect, any interest which
exceeds the maximum rate permitted under applicable laws relative to usury.

        The validity, construction, effect, performance and enforcement of this
Note shall be governed in all respects by the laws of the State of California.
Every provision of this Note is intended to be severable. Whenever possible,
each provision of this Note shall be interpreted in such manner as to be
effective and valid under applicable law, but if any provision of this Note
shall be prohibited by or invalid under such law, such provision shall be
ineffective to the extent of such prohibition or invalidity without invalidating
the remainder of such provision or the remaining provisions of this Note.

        THIS NOTE AND ALL RELATED DOCUMENTATION ARE EXECUTED VOLUNTARILY AND
WITHOUT ANY DURESS OR UNDUE INFLUENCE ON THE PART OF OR ON BEHALF OF THE PARTIES
HERETO, WITH THE FULL INTENT OF CREATING THE OBLIGATIONS AND SECURITY INTERESTS
DESCRIBED HEREIN AND THEREIN. THE PARTIES ACKNOWLEDGE THAT: (A) THEY HAVE READ
SUCH DOCUMENTS; (B) THEY HAVE BEEN REPRESENTED IN THE PREPARATION, NEGOTIATION
AND EXECUTION OF SUCH DOCUMENTS BY LEGAL COUNSEL OF THEIR OWN CHOICE OR THAT
THEY HAVE VOLUNTARILY DECLINED TO SEEK SUCH COUNSEL; (C) THEY UNDERSTAND THE
TERMS AND CONSEQUENCES OF THIS NOTE AND ALL RELATED DOCUMENTS AND THE
OBLIGATIONS THEY CREATE; AND (D) THEY ARE FULLY AWARE OF THE LEGAL AND BINDING
EFFECT OF THIS NOTE AND THE OTHER DOCUMENTS CONTEMPLATED HEREOF.



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        IN WITNESS WHEREOF, the undersigned have executed this Note, intending
to be bound personally hereby, as of the day and year first above written.


     ____________________________________
     MARK RUBASH
     BORROWER





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                                    EXHIBIT A

                       OFFER LETTER DATED JANUARY 18, 2000












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                               SECURITY AGREEMENT

     This Security Agreement is made as of January 18, 2000 between Critical
Path, Inc., a California corporation ("Pledge"), and Mark Rubash ("Pledgor").

                                    Recitals

     On January 18, 2000, Pledgor delivered a promissory note (the "Note") to
Pledgee in connection with Pledgee's loan to Pledgor in the principal amount of
$100,000.

     Pursuant to the terms of the Note, Pledgor agrees to grant Pledgee a
security interest in shares of Pledgee's Common Stock (the "Shares") issued
upon exercise of Pledgor's stock options granted under the option agreement
dated January 18, 2000 between Pledger and Pledgee (the "Option Agreement").
The Note is attached hereto as Exhibit A.

     NOW THEREFORE, it is agreed as follows:

     1.  Creation and Description of Security Interest. In consideration of the
transfer of the Shares to Pledgor under the Option Agreement, Pledgor, pursuant
to the California Commercial Code, hereby pledges all of such Shares (herein
sometimes referred to as the "Collateral") represented by a certain stock
certificate(s) issued upon exercise of Pledgor's stock options granted under
the Option Agreement, duly endorsed in blank or with executed stock powers, and
herewith delivers said certificate to the Secretary of Pledgee
("Pledgeholder"), who shall hold said certificate subject to the terms and
conditions of this Security Agreement.

     The pledged stock (together with an executed blank stock assignment for
use in transferring all or a portion of the Shares to Pledgee if, as and when
required pursuant to this Security Agreement) shall be held by the Pledgeholder
as security for the repayment of the Note, and any extensions or renewals
thereof, to be executed by Pledgor pursuant to the terms of the Note, and the
Pledgeholder shall not encumber or dispose of such Shares except in accordance
with the provisions of this Security Agreement.

     2.  Pledgor's Representations and Covenants. To induce Pledgee to enter
into this Security Agreement, Pledgor represents and covenants to Pledgee, its
successors and assigns, as follows:

          (a)  Payment of Indebtedness. Pledgor will pay the principal sum of
the Note secured hereby, together with interest thereon, at the time and in the
manner provided in the Note.

          (b)  Encumbrances. The Shares are free of all other encumbrances,
defenses and liens, and Pledgor will not further encumber the Shares without
the prior written consent of Pledgee.

          (c)  Margin Regulations. In the event that Pledgee's Common Stock is
now or later becomes margin-listed by the Federal Reserve Board and Pledgee is
classified as a "lender" within the meaning of the regulations under Part 207
of Title 12 of the Code of Federal Regulations

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("Regulation G"), Pledgor agrees to cooperate with Pledgee in making any
amendments to the Note or providing any additional collateral as may be
necessary to comply with such regulations.

     3.  Voting Rights. During the term of this pledge and so long as all
payments of principal and interest are made as they become due under the terms
of the Note, Pledgor shall have the right to vote all of the Shares pledged
hereunder.

     4.  Stock Adjustments. In the event that during the term of the pledge any
stock dividend reclassification, readjustment or other changes are declared or
made in the capital structure of Pledgee, all new, substituted and additional
shares or other securities issued by reason of any such change shall be
delivered to and held by the Pledgee under the terms of this Security
Agreement in the same manner as the Shares originally pledged hereunder. In the
event of substitution of such securities, Pledgor, Pledgee and Pledgeholder
shall cooperate and execute such documents as are reasonable so as to provide
for the substitution of such Collateral and, upon such substitution, references
to "Shares" in this Security  Agreement shall include the substituted shares of
capital stock of Pledgor as a result thereof.

     5.  Options and Rights. In the event that, during the term of this pledge,
subscription Options or other rights or options shall be issued in connection
with the pledged Shares, such rights, Options and options shall be the property
of Pledgor and, if exercised by Pledgor, all new stock or other securities so
acquired by Pledgor as it relates to the pledged Shares then held by
Pledgeholder shall be immediately delivered to Pledgeholder, to be held under
the terms of this Security Agreement in the same manner as the Shares pledged.

     6.  Default. In the event of a  Maturity Event (as that term is defined
in the Note), Pledgee shall be entitled to pursue its remedies under the
California Commercial Code.

     7.  Release of Collateral. Subject to any applicable contrary rules under
Regulation G, there shall be released from this pledge a portion of the pledged
Shares held by Pledgeholder hereunder upon payments of the principal of the
Notes or upon forgiveness of the Note. The number of the pledged Shares which
shall be released shall be that number of full Shares which bears the same
proportion to the initial number of Shares pledged hereunder as the payment of
principal bears to the initial full principal amount of the Note.

     8.  Withdrawal or Substitution of Collateral. Pledgor shall not sell,
withdraw, pledge, substitute or otherwise dispose of all or any part of the
Collateral without the prior written consent of Pledgee.

     9.  Term. The within pledge of Shares shall continue until the payment or
forgiveness of all indebtedness secured hereby, at which time the remaining
pledged stock shall be promptly delivered to Pledgor, subject to the provisions
for prior release of a portion of the Collateral as provided in paragraph 7
above.

     10.  Insolvency. Pledgor agrees that if a bankruptcy or insolvency
proceeding is instituted by or against it, or if a receiver is appointed for
the property of Pledgor, or if Pledgor makes an

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assignment for the benefit of creditors, the entire amount unpaid on the Note
shall become immediately due and payable, and Pledgee may proceed as provided
in the case of default.

     11.  Pledgeholder Liability. In the absence of willful or gross
negligence, Pledgeholder shall not be liable to any party for any of his acts,
or omissions to act, as Pledgeholder.

     12.  Invalidity of Particular Provisions. Pledgor and Pledgee agree that
the enforceability or invalidity of any provision or provisions of this
Security Agreement shall not render any other provision or provisions herein
contained unenforceable or invalid.

     13.  Successors or Assigns. Pledgor and Pledgee agree that all of the
terms of this Security Agreement shall be binding on their respective
successors and assigns, and that the term "Pledgor" and the term "Pledgee" as
used herein shall be deemed to include, for all purposes, the respective
designees, successors, assigns, heirs, executors and administrators.

     14.  Governing Law. This Security Agreement shall be interpreted and
governed under the internal substantive laws, but not the choice of law rules,
of the State of California.

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        IN WITNESS WHEREOF, the parties hereto have executed this Agreement as
of the day and year first above written.


        "PLEDGOR"
                                               --------------------------------
                                               Signature


                                               --------------------------------
                                               Print Name

                                Address:
                                               --------------------------------


                                               --------------------------------

        "PLEDGEE"                              Critical Path, Inc.,
                                               a California corporation


                                               --------------------------------
                                               Signature


                                               --------------------------------
                                               Print Name


                                               --------------------------------
                                               Title

        "PLEDGEHOLDER"
                                               --------------------------------
                                               Secretary of Critical Path, Inc.





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