ietf-smtp
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Re: [ietf-smtp] SMTP server reply extensions

2020-04-08 09:31:59
On 08/04/2020 15:00, Timo Sirainen wrote:
1. IMAP-like login referrals (RFC 2221)

This RFC isn't really used nowadays, but I'm now thinking of using referrals 
internally in Dovecot clusters. Dovecot backend could send a referral and 
Dovecot proxy would reconnect to that referral instead. But the same thing is 
needed also for LMTP, which means that it would have to be sent in a RCPT TO 
reply since the redirection can be different for different users. Perhaps 
something like:

RCPT TO:<user(_at_)example(_dot_)com>
250 2.1.5 OK
RCPT TO:<user2(_at_)example2(_dot_)com>
450 4.4.4 [REFERRAL smtp://backend2/] Redirected
RCPT TO:<user3(_at_)example3(_dot_)com>
450 4.4.4 [REFERRAL smtp://backend3/] Redirected

Perhaps this?

RFC 4321 Section 4.2.3
  551  User not local; please try <forward-path>


-- 
Cheers,
  Jeremy

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