Author: Jeremy Harris Date: To: exim-users Subject: Re: [exim] exim 4.89 + "no host found for existing SMTP connection"
On 19/01/18 10:33, Urs Janßen wrote: > after switching to a new upstream mailprovider we see tons of
> "T=remote_smtp defer (-53): no host found for existing SMTP connection"
> in our log, comming from a manual router which passes all remaining
> mails to the provider:
>
> send_to_gateway:
> driver = manualroute
> transport = remote_smtp
> route_list = * smtp.provider.example
>
> smtp.provider.example usualy resolves to a _different_ A record on each dns
> query (4-5 in total) but does NOT do dns round robin (does not return a list
> of records but a single entry each time).
>
> Any ideas how to fix this issue on our side?
More of a workaround than a fix (it reduces efficiency) - try setting
connection_max_messages = 1
on the transport.
Alternatively, use a caching DNS resolver to proxy your DNS lookups.
--
Cheers,
Jeremy
