Dovecot – login_greeting new line character

I am using this login_greeting for IMAP(S) protocol:

protocol imap {
  login_greeting = "mail.pistam.eu -------> "WELCOME TO PORT 993!""
}

I want to know if it’s possible to add a new line character at the beginning of the string? This doesn’t work:

protocol imap {
  login_greeting = "nmail.pistam.eu -------> "WELCOME TO PORT 993!""
}

And this reports an error because it looks like configuration parameters have to be in one line:

protocol imap {
  login_greeting = "
  mail.pistam.eu -------> "WELCOME TO PORT 993!""
}

Any other idea?