S1 Teams With PayPal to Deliver Fast, Convenient Mobile Personal Payments Solution...

S1 Teams With PayPal to Deliver Fast, Convenient Mobile Personal Payments
Solution for Banks

NORCROSS, Ga., Nov. 3, 2009 (GLOBE NEWSWIRE) -- S1 Corporation (Nasdaq:SONE), a
leading global provider of financial services and payments software solutions,
today announced an agreement with PayPal to deliver a new personal payments
service that allows consumers and businesses to make easy, fast and secure
payments from their bank accounts to PayPal users around the world using their
mobile phones. Mercantile Bank of Michigan, a customer of S1, is the first
financial institution to sign up for the new offering and expects to go live
with the mobile personal payments service early next year.

"S1's continued innovation in mobile banking and integration with the PayPal
network will give us a competitive edge to support a channel that is essential
to our customers and strategic to our bank's future," said John Schulte, senior
vice president and CIO for Mercantile Bank of Michigan. "We see tremendous value
for our customers in expanding our mobile banking functionality to include
person to person payments with PayPal."

The S1 and PayPal alliance enables banking customers to quickly send money to
PayPal customers from their mobile device by entering the recipient's email
address or mobile phone number. In order to complete the transaction, the sender
just needs to have a bank account with a participating financial institution and
the receiver needs to have a PayPal account.

If the receiver does not have a PayPal account, he or she will be prompted to
create one before funds can be transferred into his or her account. There are no
other enrollment requirements. The sender will receive a real-time status alert
of whether the funds sent have been claimed, effectively providing full insight
into the transaction. Financial institutions working with S1 can tailor pricing
for this new offering to maximize fee-based opportunities.

"S1 is the first company to announce their intention to utilize the PayPal
platform to deliver personal payments for banks across the mobile channel," said
Dan Schatt, senior director and head of financial innovations, PayPal. "This new
relationship creates terrific opportunities for banks to offer valuable,
differentiated services to their customers, and is a great example of how
collaboration with financial services technology providers like S1 can help fuel
a major expansion of the reach and use of mobile personal payments."

"This deal reflects the growing functionality of the mobile channel and is a
strong signal to banks of where customer expectations are headed," said Bob
Egan, global head of research and chief analyst at TowerGroup, a market research
firm based in Needham, MA. "Given the near-ubiquity of mobile devices and fast
adoption of smart phones in particular, we can expect an increasing convergence
of trusted banking relationships, personal payments and mobile."

Schulte added that instant and easy access to making secure payments on the go
has an endless array of uses that offer consumers flexibility in handling day to
day needs. "Any spur of the moment need for making a quick payment when you are
on the go is a great opportunity to use the mobile channel, and it eliminates
the hassle of finding an ATM or dealing with checks. Paying the babysitter,
splitting the restaurant tab, getting money to the kids, or collecting funds for
a group gift are just a few examples. All the recipient needs is an email
address or cell phone number," he said.

"The strategic alliance with PayPal is just one example of S1's commitment to
advance its strategy of 'universal money movement,' enabling banking customers
to make payments and move money anytime, anywhere and through any channel
worldwide," said Jan Kruger, S1 Division President. "By working with PayPal to
offer an easy way to pay almost anyone from anywhere through a mobile device, we
help banks forge deeper relationships with their customers through an incredibly
useful new service."

About S1 Corporation

Leading banks, credit unions, retailers, and processors need technology that
adapts to the complex and challenging needs of their businesses. These
organizations want solutions that can respond quickly to changes in the
marketplace and help grow their businesses. For more than 20 years, S1
Corporation (Nasdaq:SONE) has been a leader in developing software products that
offer flexibility and reliability. Over 3,000 organizations worldwide depend on
S1 for payments, online banking, mobile banking, voice banking, branch banking
and lending solutions that deliver a competitive advantage. More information is
available at www.s1.com.

About Mercantile Bank of Michigan

Based in Grand Rapids, Michigan, Mercantile Bank Corporation is the bank holding
company for Mercantile Bank of Michigan. Founded in 1997 to provide banking
services to businesses, individuals, and governmental units, the Bank
differentiates itself on the basis of service quality and its banking staff
expertise. Mercantile has seven full-service banking offices in Grand Rapids,
Holland, and Lansing, Michigan. Mercantile Bank of Michigan's common stock is
listed on the NASDAQ Global Select Market under the symbol "MBWM". More
information about the company can be found at www.mercbank.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.

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CONTACT: S1 Corporation
David Fontaine
404.923.6865
David.Fontaine@s1.com