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  1. #1
    Join Date
    Aug 2013
    Posts
    42

    Hard Mail Bounces when VPS Server is Down?

    My VPS server from a hosting company experienced a 3 hours downtime yesterday.

    I immediately tested if emails being sent to me (on that VPS server) during that time will not experience hard mail delivery failures, through my Yahoo Mail test account.

    However, I experienced below error message sent from my Yahoo Mail test account after just about 1 hour:
    -----
    Sorry, we were unable to deliver your message to the following address.
    <user@mydomain.com>:
    No MX or A records for mydomain.com
    -----

    Because of the above, I'm worried that there were important emails that were sent to me during that downtime and that there's a possibility that they may not be aware that I didn't receive it--therefore a loss in business.

    My question is:

    1. I thought server downtimes will just trigger soft bounces and most mail servers (in this case Yahoo Mail), will retry sending mails let's say up to three days. Why is it that the downtime in VPS servers will result to mail hard bounces?

    2. Is it really true that when a VPS server is down for even just a few hours, the MX or A records will immediately not resolve and so will cause hard bounce/permanent mail delivery failure?

  2. #2
    Join Date
    May 2009
    Location
    Vaduz/LI
    Posts
    2,778
    Your DNS is hosted on the same server and has no fallback DNS - Thus your DNS is down, thus it can't resolve, thus you get a hard bounce.

    Solution: Use external DNS provider or a slave DNS as secondary nameserver

  3. #3
    Join Date
    Aug 2013
    Posts
    42
    My registrar and web hosting are on two separate companies. Where will I modify the fallback DNS, is it through my registrar? or through my web host?

  4. #4
    Join Date
    Aug 2013
    Posts
    42

    Question

    I would like to revive this thread as I'm beginning to learn a little bit on how this DNS thing works but need some new clarification.

    As you can see from my previous posts, I'm still with the same VPS hosting company. Because this is a VPS I can only use private nameservers, namely ns1.mydomain.com and ns2.mydomain.com , meaning to say the DNS is hosted on the same server.

    I understand that there are alternatives like using a 3rd party DNS host so that even if the VPS server is down, the DNS is working and mail transfer agents (like Yahoo Mail, Gmail) can try resending up to 3 days. But I'm not comfortable on going this route because I'm not that expert and I might mess up some settings because of added steps, and may only result to significant downtime in case there will be error in my settings.

    One day, I was thinking of moving to a new VPS provider and found Wiredtree being mentioned several times in WHT. I also found that I can be given two choices of DNS, whether it is private ns1.mydomain.com, OR I can use ns1.wiredtree.com and ns2.wiredtree.com .

    Now my question is this, If I understand it correctly, If I am going to use Wiredtrees own nameservers, instead of my own domains private nameservers, is it safe for me to say, that in the case that my VPS node or container/server is down, the DNS can still be resolved by mail transfer agents (senders from Gmail, Yahoo, etc.) and will just keep trying up to 3 days? At least it won't be a hard bounce. Please let me know if my understanding is correct and accurate. Thanks.

  5. #5
    Join Date
    Mar 2003
    Location
    /root
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    23,991
    Quote Originally Posted by yagami_kira View Post
    As you can see from my previous posts, I'm still with the same VPS hosting company. Because this is a VPS I can only use private nameservers, namely ns1.mydomain.com and ns2.mydomain.com , meaning to say the DNS is hosted on the same server.
    Any providers can setup private nameservers for you especially if this is VPS.

    Specially 4 U
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  6. #6
    Join Date
    Aug 2013
    Posts
    42
    Quote Originally Posted by net View Post
    Any providers can setup private nameservers for you especially if this is VPS.
    Yes, I knew VPS providers just give out private nameservers. But that means the DNS is hosted in the VPS server. So if the server is down, the DNS host is also down, which is not good. But what if I use the VPS provider nameservers instead of private? So even if the VPS server is down, but the VPS provider DNS nameserver is up, then hard mail bounce can be prevented, is that correct?

  7. #7
    Join Date
    Jun 2011
    Location
    Internet
    Posts
    2,985
    Honestly I'd recommend just using a third party's DNS -- e.g. cloudflare, pointhq, rage4, your domain registrar, etc. If your VPS provider offers nameservers and they go down at the same time as your VPS (e.g. a network or power outage); you're out of luck!

    If you do want to go ahead and host your own though; have NS1 and NS2 on different servers in different locations. That way if one goes down, your mail should still be OK.

  8. #8
    Join Date
    Jan 2011
    Location
    Dallas, TX
    Posts
    2,121
    CloudFlare is a great (free) option for DNS management. I use it and I'm sure most hosts here use it.
    ExtraVM - DDoS Protected NVMe VPS, Website Hosting, & Game Servers
    Dallas, TX | Miami, FL | Los Angeles, CA | Piscataway, NJ | Amsterdam, NL | Singapore | Tokyo, JP

  9. #9
    Join Date
    Mar 2009
    Location
    Here Today - Gone to Maui
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    9,966
    Since your primary concern is hard bounces, I agree with Mike that CloudFlare would be a viable solution.
    ProlimeHost - Dedicated Server Hosting & KVM SSD VPS
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  10. #10
    Join Date
    Aug 2013
    Posts
    42
    Finally, I have an opportunity to test this issue further. I'll post my findings here for record purposes and also to help guide other people as well.

    I forced one of my server (VPS server using private nameservers) to go down and did test mails with different major email providers.

    The results so far:

    1. Yahoo - bounced after 30 minutes
    2. AOL - bounced after 30 minutes (funny that even by using third pary DNS (registrar DNS), AOL will still bounce the mail after 30 minutes without even retrying at a later time)
    3. Gmail - 6 hours had passed and still retrying
    4. Hotmail - 6 hours had passed and still retrying
    5. Zoho Mail - will retry for 5 more days
    6. cPanel webmail - 6 hours had passed and still retrying

    Will update this post in a few days....

  11. #11
    Join Date
    Aug 2013
    Posts
    42
    It's been 2 days and I've decided to turn the server back on. The results and in conclusion:

    1. Yahoo - hard bounce after 30 minutes

    Code:
    Sorry, we were unable to deliver your message to the following address.
    
    <help@example.com>:
    No MX or A records for example.com
    1.1 Yahoo (third party DNS) hard bounce after 1 day

    Sorry, we were unable to deliver your message to the following address.

    Code:
    <help@example.com>:
    Mail server for "example.com" unreachable for too long :

    2. AOL - hard bounce after 30 minutes regardless if using third party DNS or private nameservers

    Code:
    <help@example.com>: Host or domain name not found. Name service error for
    name=example.com type=MX: Host not found, try again
    
    <help@example.com>: connect to
    example.com[123.45.678.90]:25: Connection timed out

    3. Gmail - will retry for 3 days
    4. Hotmail - 2 days had passed and still retrying
    5. Zoho Mail - will retry for 5 days
    6. cPanel webmail - 2 days had passed and still retrying


    AOL so far is the laziest MTA. They won't bother to retry if your server is down for 30 minutes.

  12. #12
    Join Date
    Aug 2013
    Posts
    42
    I've successfully migrated the DNS to Cloudflare Managed DNS (not the orange cloud CDN feature) so I'm now using cloudflare nameservers to avoid these hard mail bounces.

    I've decided to use Cloudflare DNS as mentioned in this thread instead of my registrar (Godaddy) because a quick search in twitter shows that even Godaddy DNS can suffer from downtime in some countries, sometimes lasting several hours.

    I don't see news about cloudflare DNS going down sometimes, or maybe I just overlooked it? Is Cloudflare DNS uptime really great nowadays than the ones provided by domain registrars?

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