Your temporary password for SalesMail likely includes one or more special characters (e.g. @,!,%,$,^,#,&,*).  The best way to make sure you are typing in the exact same temporary password is to highlight the password in the welcome email and copy it (press the CTRL key and C key at the same time) and then paste it into the password box on the salesmail login screen (click your mouse in the password box and then press the CTRL key and the V key at the same time).  This should ensure that you are typing in the correct temporary password.  If it does not work, click the 'Forgot passord' link to get a new temporary password.