1 Topic by thinkwell (edited by thinkwell 2015-04-07 23:35:36)

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Topic: 550-Requested action not taken: mailbox unavailable 550 invalid DNS

I'm using iRedMail 0.8.7 on Ubuntu 14.04, hosting multiple domains. I'm not able to send emails to 1and1 hosted accounts. Emails to 1and1-hosted addresses bounce back with:

Action: failed
Status: 5.0.0
Remote-MTA: dns; mx01.1and1.com
Diagnostic-Code: smtp; 550-Requested action not taken: mailbox unavailable 550
    invalid DNS MX or A/AAAA resource record


I'm pulling my hair out. I have MX records, SPF records, DKIM keys, reverse DNS. All DNS tests pass for thinkwell.io on MXToolbox. Can't figure out why 1and1 complains that my MX records are invalid.

Any help / suggestions on getting mail delivered to 1and1?

----

Spider Email Archiver: On-Premises, lightweight email archiving software developed by iRedMail team. Supports Amazon S3 compatible storage and custom branding.

2 Reply by 7t3chguy

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Re: 550-Requested action not taken: mailbox unavailable 550 invalid DNS

The error seems like the recipient e-mail domain is broken, that mx01.1and1.com is unaware of the mailbox you are trying to reach.

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3 Reply by thinkwell

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Re: 550-Requested action not taken: mailbox unavailable 550 invalid DNS

7t3chguy wrote:

The error seems like the recipient e-mail domain is broken, that mx01.1and1.com is unaware of the mailbox you are trying to reach.

That's what I thought too, but the address is reachable from other mail servers. Also, the problem exists on multiple 1and1-hosted email domains. So it seems to be a more generalized problem. I am taking it up with 1and1 support, but not being a customer myself, I'm not sure how well that will go. Will post back if I get answers from 1and1.

Meanwhile, if there are any further thoughts, I'm all ears.

4 Reply by ZhangHuangbin

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Re: 550-Requested action not taken: mailbox unavailable 550 invalid DNS

I suggest double check A/MX records. Maybe you should let us know your mail domain name, so that others can help verify it.

5 Reply by pauljsmith4 (edited by pauljsmith4 2015-04-15 23:52:37)

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Re: 550-Requested action not taken: mailbox unavailable 550 invalid DNS

We had a similar issue.

We got this response from 1and1.

Please be informed that we checked the error message that you have provided and discovered that [OUR COMPANY NAME] is using a reverse ip configuration which is not supported by shared hosting packages. Note that the problem lies with the mx configuration of [OUR COMPANY NAME] and not your email address((HELO mail.[OUR COMPANY NAME].com)). Their MX servers uses a CNAME configuration is which not a valid server as shown below.Please let them review (http://tools.ietf.org/html/rfc2181#section-10.3).

So basically when you do

dig MX mail.[OUR COMPANY NAME].com

you want the answer to show an answer which is a DNS A record entry, if it shows a CNAME record it doesn't like it.

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6 Reply by ZhangHuangbin

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Re: 550-Requested action not taken: mailbox unavailable 550 invalid DNS

Thanks for sharing, Paul.

7 Reply by doahh (edited by doahh 2015-04-24 16:12:58)

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Re: 550-Requested action not taken: mailbox unavailable 550 invalid DNS

I am having a similar issue with an email from 'jtprojects dot com' who uses 1and1 for their email service. They are unable to send emails to me at 'talkingcouch dot uk' and get the following bounce error:

Server error: '550 invalid DNS MX or A/AAAA resource record'

I am a little unsure about how to implement your advice. I tried to remove the CNAME record for talkingcouch but that seemed to prevent me receiving emails from other accounts such as Gmail. My DNS has:

talkingcouch.uk.                                 A                      54.229.217.48
mail.talkingcouch.uk.                    CNAME        talkingcouch.uk
talkingcouch.uk.                                MX                    10 mail.talkingcouch.uk
talkingcouch.uk.                                PTR                   ec2-54-229-217-48.eu-west-1.compute.amazonaws.com
talkingcouch.uk.                                SOA                   ns-1723.awsdns-23.co.uk. awsdns-hostmaster.amazon.com.

Can anyone clarify the suggestions for a sysadmin novice please?

8 Reply by lacoursj

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Re: 550-Requested action not taken: mailbox unavailable 550 invalid DNS

I have the same issue with 1and1, and no one else.  I have two domains, neither of which can send mail to 1and1 hosted users.  I get "mailbox unavailable 550 invalid DNS MX or A/AAAA resource" when I try to email them, though the same recipient works fine from my google hosted domains.  Very frustrating.

I have no CNAMEs in my DNS, my mail.<company>.com is an A record, and matches the MX record for <company>.com.  The reverse record for that IP is a generic name - the same IP hosts a number of mail domains for myself an others, but the name that is returned by the reverse properly resolves as an A record to the same IP.   I have no idea what 1and1 is complaining about.

Any other clues?  Actually happy for interested parties to examine my setup - jeff.net.

Cheers!

9 Reply by ZhangHuangbin

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Re: 550-Requested action not taken: mailbox unavailable 550 invalid DNS

Did you guys try to contact 1and1?

10 Reply by doahh

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Re: 550-Requested action not taken: mailbox unavailable 550 invalid DNS

ZhangHuangbin wrote:

Did you guys try to contact 1and1?

I have now emailed sales@1and1.co.uk (the only address I could find) with the following:

I am not a customer but one of your customers has had trouble getting email through to me. When he sends an email it bounces with:

    Server error: '550 invalid DNS MX or A/AAAA resource record'

This thread details several people with the same problem:

    http://www.iredmail.org/forum/post38380.html#p38380

All tests using mxtoolbox.com pass for my domain but for your customer the SMTP test gives:

    SMTP Reverse DNS Mismatch     Warning - Reverse DNS does not match SMTP Banner

Do you have any advice as to how I can receive mail from any of your customers who use your email services? I am not alone in facing this issue and hence think that this may be something at your end.

11 Reply by doahh (edited by doahh 2015-04-24 19:22:31)

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Re: 550-Requested action not taken: mailbox unavailable 550 invalid DNS

I got a response from 1and1:

As we have verified from our higher department, the reason why 1&1 email users are unable to send you an email it is because we had determined that the MX records of your domain is using a CNAME record. As per http://tools.ietf.org/html/rfc2181#section-10.3, CNAME records should not be used for MX records as well as for Nameservers. Having a CNAME as an MX record never works well or it can never serve its purpose as an MX record. We advise that you check on this as this is not an issue with the 1&1 mailservers. We appreciate your patience and understanding with the matter on hand.

Which is pretty much the same answer as pauljsmith4 posted above.

I have changed the CNAME record mail.talkingcouch.uk to an A record. I've asked the person to re-send the email and test to see if that works.

12 Reply by 7t3chguy

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Re: 550-Requested action not taken: mailbox unavailable 550 invalid DNS

DNS Providers/DNS Servers should enforce A Records for MX
But this isn't an ideal world
I think CloudFlare does, but CloudFlare is something else.

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13 Reply by doahh (edited by doahh 2015-04-24 19:34:41)

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Re: 550-Requested action not taken: mailbox unavailable 550 invalid DNS

7t3chguy wrote:

DNS Providers/DNS Servers should enforce A Records for MX
But this isn't an ideal world
I think CloudFlare does, but CloudFlare is something else.

I am not a very competent sysadmin. I am using AWS's Route53 DNS interface. I have:

talkingcouch.uk.            MX        10 mail.talkingcouch.uk
mail.talkingcouch.uk.    A           54.229.217.48

Does that look about right?

14 Reply by 7t3chguy

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Re: 550-Requested action not taken: mailbox unavailable 550 invalid DNS

Yeah, just give it some time to propagate and try again

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