I suppose it is reasonable to be suspicious of
the anonymous messaging facility but it really is anonymous.
Only the provided information comes through, nothing is collected or added by the web form or the transmission system.
If I could be bothered, and until today I haven’t, an old fashioned email client such as Microsoft’s Outlook can check the routing of an email. That cannot be suppressed. Outlook reports that the email below came from an email server called github whatever that may be. Beyond that I know nothing about the source. The same would be true if it included attachments.