Envelope

Envelopes encapsulate the characteristics of a mail, used by the mail receiver to determine how to handle the mail post-receival. Envelopes are assembled by the mail sender.

pub struct Envelope {
    destination: AccountInfo, // null for multicasting next version
    
    //execution_dependency: Option<MailId>, # next version 

    opener: Option<AccountInfo>, 
    response_of: Option<MailId> 
}

Key	Type	Description
destination	AccountInfo	Destination account details of mail. null for a multicast to all supported chains.
execution_dependency	Option<MailId>	ID of mail that should be executed prior to this mail's execution.
opener	Option<AccountInfo>	Address details of designated mail opener. null to allow anyone (including relayers) to open mail on behalf of receiver. Possible use for contracts to include mail opening within execution of certain logic.
response_of	Option<MailId>	ID of mail that triggered this mail. Filled if mail is a response to a previous mail.