EXHIBIT 99.1

PRESS RELEASE


S1 CORPORATION ANNOUNCES PRELIMINARY FINANCIAL RESULTS FOR FIRST QUARTER 2003


ATLANTA, April 7 -- S1 Corporation (Nasdaq: SONE - News), a leading global
provider of Enterprise solutions for the financial services industry, announced
an update to its financial outlook for first quarter 2003. S1 expects its first
quarter 2003 loss to be within the range of ($0.11) to ($0.13) per share, as
compared with its previously announced expectations for earnings within a range
of a loss of ($0.02) per share to a profit of $0.01 per share. The expected loss
includes charges of ($0.11) per share resulting from costs associated with
restructuring and cost containment measures described below. S1's first quarter
2003 revenue is expected to be $58 million to $60 million, versus its previous
revenue guidance of $57 million to $60 million. The company will discuss its
expectations for financial results for the full year 2003 during its quarterly
earnings conference call scheduled for May 1. "We met our revenue goals for Q1;
however we continue to experience an economic environment that elongates sales
and implementation cycles," said Jaime Ellertson, S1 Chief Executive Officer.
"Our principal focus for 2003 centers on building a long-term stable Enterprise
customer base. This focus in combination with the current difficult market
conditions leads us to re-evaluate our revenue expectations for the remainder of
the 2003 calendar year. We will update our revenue and earnings guidance on our
first quarter earnings conference call."

         A combination or restructuring and other cost containment measures
during the first quarter will result in a net impact of ($0.09) per share on
first quarter earnings and an expected net impact of $0.02 per share on second
quarter earnings. An explanation of the impact of these charges on the company's
financial results follows:

                                                  Q1 2003          Q2 2003
                                             ---------------   --------------
                                             (in millions except per share data)


Acceleration of contract (1)
    Revenue from customer contract                    $1.6             $4.7
    Direct costs associated with contract             (0.4)            (0.4)
Net impact of contract acceleration                   $1.2             $4.3
EPS impact of contract acceleration                  $0.02            $0.06

Restructuring Expense
    Costs associated with consolidation of
      global data center (2)                          (2.3)            (2.5)
    Loss on excess facilities (3)                     (2.6)              --
    Other restructuring charges (4)                   (2.7)              --
Net impact of restructuring charges                  ($7.6)           ($2.5)
EPS impact of restructuring                         ($0.11)          ($0.04)

Shares used in calculation                            69.0             69.0

(1)    During the first quarter, S1 amended its contract with a major European
       customer to shorten the term over which revenue will be recognized and
       payments received associated with the provision of data center services
       by S1. Revenue from the data center contract, which would have been
       recognized ratably throughout 2003 and 2004 under the previously amended
       terms of the agreement, will be


     recognized in the first and second quarters of 2003. Associated direct
     costs will be accelerated as well.

(2)  S1 is consolidating its U.K. data center operations into its global hosting
     center in Atlanta,  triggering restructuring charges comprising accelerated
     depreciation of assets, severance and other related costs.

(3)  The company  provided for losses on unused office  facilities  vacated as a
     result of cost alignment activities.

(4)  Other  restructuring  charges included severance and other costs associated
     with a force reduction in Asian  operations as well as other  miscellaneous
     corporate charges.

     S1's final first  quarter  results will be  announced  on Thursday,  May 1,
2003, after the close of market. These results, along with S1's business outlook
for the year, will be discussed on a conference call and simultaneous webcast to
be held at 5:00 p.m.  EDT that same day.  The webcast of this  conference  call,
which will be available live as well as on an archived basis, can be accessed by
all interested parties at S1 Corporation's website, www.s1.com.

ABOUT S1 CORPORATION

S1 (Nasdaq: SONE - News) is a leading global provider to approximately 4,000
banks, credit unions, insurance providers, and investment firms of enterprise
software solutions that create one view of customers across multiple channels,
applications and segments. S1's Enterprise software solutions uniquely combine
customer interaction and financial transaction capabilities, resulting in a more
compelling experience for the customers and a more profitable relationship for
the financial institution. S1 is the only provider with the proven experience,
breadth of products, and financial strength to empower financial services
companies' enterprise strategies. Additional information about S1 is available
at www.s1.com.

FORWARD-LOOKING STATEMENTS

This press release contains forward-looking statements within the safe harbor
provisions of the Private Securities Litigation Reform Act. These statements
include statements with respect to our financial condition, results of
operations and business. The words "believes," "expects," "may," "will,"
"should," "projects," "contemplates," "anticipates," "forecasts," "intends" or
similar terminology identify forward-looking statements. These statements are
based on our beliefs as well as assumptions made using information currently
available to us. Because these statements reflect our current views concerning
future events, they involve risks, uncertainties and assumptions. Therefore,
actual results may differ significantly from the results discussed in the
forward-looking statements. The risk factors included in our reports filed with
the Securities and Exchange Commission (and available on our web site at
www.s1.com or the SEC's web site at www.sec.gov) provide examples of risks,
uncertainties and events that may cause our actual results to differ materially
from the expectations we describe in our forward-looking statements. Except as
provided by law, we undertake no obligation to update any forward-looking
statement.