Encoded Data Checksum Mismatch - Attachment may be corrupted
What happened
The attachment you tried to use is unusable by IBM® Notes®.
What you can do
Ask the sender of the message, or the creator of the document in a non-mail application, to create the attachment again.
If the attachment is in a mail message, delete the entire message (with attachment) and ask the sender to send a new message with a new attachment.
If the attachment is in a non-mail document, have the author delete the original attachment and then create a new document with a new attachment.