We had that issue several times.
Please check if the path "C:\ISTS\PDFS\" exist and it is correct.
Check if the SMTP port is corrent: "1025". if you are not sure what it is check your email software (MS Outloook?)
Once your email is working again. Make a copy of your "C:\ISTS\EvoSettings.INI"
Save it some where other than the "C:\ISTS\" folder.
Kelloggs