Yes,but you do not want the email to contain the text “file:///C:/openhab/conf/html/carport/ipcamera.gif”. You are expecting the sendmail to go off, find that file, and put the contents of that file in your email.
So if it cannot find the file, or cannot encode the file content for mailing, it will blow up even if the actual attachmentUrlList variable is populated. Blowing up with ‘null’ is not I would have expected, though.
Maybe whatever prepares the file is taking longer than it used to.