if (recipientAST instanceof SystemPostmasterRecipientAST) {
SystemPostmasterRecipientAST systemPostmasterAST =
(SystemPostmasterRecipientAST) recipientAST;
return new GlobalPostmaster(systemPostmasterAST.postmasterSpelling);
} else if (recipientAST instanceof DomainPostmasterRecipientAST) {
DomainPostmasterRecipientAST domainPostmasterAST =
(DomainPostmasterRecipientAST) recipientAST;
Mailbox mailbox = createMailbox(domainPostmasterAST.mailboxAST);
return new DomainPostmaster(mailbox);
} else if (recipientAST instanceof MailboxRecipientAST) {
MailboxRecipientAST mailboxRecipientAST =