# Known problems
# Explain to the recipients
Cautious people may be suspicious and refuse to open the `.shtml' file for fear that it is a malicious file. This is to their credit! At Seald, we can only congratulate them on their mistrust.
However, in this case, it is not a malicious file, a page has been specially written for them to explain it: https://seald.io/how-to-decrypt. You can add this link to your exchanges to explain to them.
When you click on the
.shtml file from Gmail to preview it, a temporary 404 error may appear:
In this case, you must first download the attachment and then open it.
# No application can open this format
If you have Seald, check in the application preferences that the Seald file format is correctly associated.
If one of your contacts reports this problem, he probably only has Microsoft Edge, which is installed by default on Windows as a browser. This does not open
.shtml files by default. In this case, go to Seald Secure Reader and drag and drop your Seald file.