Shares of Pitney Bowes ( PBI) plunged 12% in late trading Monday after the company posted a weaker-than-anticipated third-quarter profit.The mail services and postage-meter concern also forecast more weakness for the fourth quarter and cut its full-year earnings outlook. Shares were down $5.49 to $41.50 in after-hours trading. For the third quarter, Pitney Bowes' net income fell to $127.7 million, or 58 cents a share, from $148.6 million, or 66 cents a share, a year earlier. Adjusted earnings, which exclude restructuring and accounting-related charges, fell to 63 cents a share from 66 cents. Those results were below Pitney Bowes' guidance of 70 cents to 74 cents, as well as analysts' average estimate of 74 cents. The Stamford, Conn., company said third-quarter revenue rose to $1.51 billion from $1.43 billion. Analysts expected a top line of $1.56 billion, according to Thomson Financial. "Business conditions during the third quarter were much more challenging than we originally anticipated," said President and CEO Murray Martin. "Our Software and Mail Services segments continued to have very strong results, but their performance was offset by weakness in our U.S. and International Mailing segments as well as in our Management Services segment." Martin said results were hit by factors such as weakness in financial services, a timing shift in U.S. postal sales and delays in postal liberalization across Europe. For the fourth quarter, Pitney Bowes forecast adjusted earnings of 67 cents to 71 cents a share, below Wall Street's 84-cent forecast. The company now sees full-year earnings of $2.67 to $2.71 a share, below its July guidance of $2.90 to $2.98. Analysts project 2007 earnings of $2.94 a share.