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I need to send mail from but delivery to one address fails with an error "R=lookuphost defer (-1): host lookup did not complete".

Additional information that might be relevant: My /etc/resolv.conf contains nameservers of a VPS provider (different from domain provider's nameservers). I also checked DNS records of the addressee and found out there was no MX record for it.

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You should explain what the problem is, not what you think the solution is. – Michael Hampton Mar 31 '14 at 14:42
thank you, I edited my question – hiirulainen Mar 31 '14 at 16:01
1. Just because there is no MX record, it does not mean that mail cannot be sent there an A record is valid in absence of an MX record. 2. Does this VPS provider's DNS do recursive lookups for you? – NickW Mar 31 '14 at 16:02
@NickW I think it does not do recursive lookup. I checked it by "host vps_providers_nameserver" and it returned REFUSED; also dig nameserver returned "recursion requested but not available" – hiirulainen Mar 31 '14 at 16:43
That's not good, you want to configure a DNS server that will do recursive lookups for you, especially if you want to run a mailserver. – NickW Mar 31 '14 at 16:49
up vote 2 down vote accepted

check if MX DNS resolution fails from your side or not with

  • if you don't have MX results. exim should fallback to A record. cf exim FAQ (check Q0311 too)

use exim -bt -d-resolver to diagnose exim mail routing

  • if yes. it means DNS resolution fails on your side.

run nslookup -type=MX on your server. and check if you get MX records answers.

if not, try the same request but specify a well known nameserver, like google public dns: nslookup -type=MX

you should now get some MX results, and it means your nameserver is not working properly. So you can change your resolv.conf to a nameserver that works properly (provider, google dns, what you want, ..) or setup your own

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thank you! If I don't get any MX results for but get them for, does it count? – hiirulainen Mar 31 '14 at 17:35
Not to my knowledge. the only one fallback is A record – exeral Mar 31 '14 at 18:18
one last question! if exim -bt -d-resolver succeeds but exim -bt -d-resolver fails, doesn't it mean that the problem is with and not with me? – hiirulainen Mar 31 '14 at 18:40
besides, when I do dig @ I get status: SERVFAIL and no answer section. And is the only domain I'm having such problems with, all my other addressees are able to get emails from me – hiirulainen Mar 31 '14 at 18:49
it means the nameserver of is unreachable, misconfigured. the problem is not on your side – exeral Mar 31 '14 at 19:30

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