Help with GMail...


I was wondering if there were any GMail contacts on NANOG that might contact me either on or off list for some help.

I am having problems sending email to GMail from my new (< 2 weeks old) Linode VPS. (IPv4:, IPv6: 2600:3c00:f03c:91ff:fe26:8849)

I have forward and reverse DNS set up as well as following all of the same practices that I have used to administer email servers for the past 15 years. So, I think that I have everything covered. (If I've missed something, let me know and I'll take care of it.)

Is there a chance that my IP address(es) (v4 and / or v6) have been blocked because of previous IP user actions? Or am I by chance part of a netblock that is black listed?

Below is the multi-line SMTP response that is showing up in the DSN that I'm receiving.

<<< 550-5.7.1 [2600:3c00::f03c:91ff:fe26:8849 12] Our system has detected that
<<< 550-5.7.1 this message is likely unsolicited mail. To reduce the amount of spam
<<< 550-5.7.1 sent to Gmail, this message has been blocked. Please visit
<<< 550 5.7.1 for more information. f5si4126138oeo.56 - gsmtp

Any help or suggestions you could provide would be greatly appreciated. I'm in the process of migrating off of my old server to my new Linode VPS as part of a move and would like to get this quickly, if possible.

As a temporary work around, I have routed email to my other Linode which can send email to GMail. (IPv4:, IPv6: 2a01:7e00::f03c:91ff:fe89:2935)

Thanks for your time and any help you can provide.

Kudos to Gareth T. who pointed out that I forgot to update my SPF record, which includes a "-all".

I've updated my SPF record and will try again after my old info expires out of caches.

$ host 2600:3c00:f03c:91ff:fe26:8849
Host 2600:3c00:f03c:91ff:fe26:8849 not found: 3(NXDOMAIN)

you probably also want to fix that...

Hi Christopher,

Unless my eyes are deceiving me, I think "host" ate a colon in "::" for you.

I *think* that I have forward and reverse DNS set up properly for both IPv4 and IPv6.

#[gtaylor@tncsrv04:~]$ dig a 3600 IN A

#[gtaylor@tncsrv04:~]$ dig -x 86400 IN PTR

#[gtaylor@tncsrv04:~]$ dig aaaa 3600 IN AAAA 2600:3c00::f03c:91ff:fe26:8849

#[gtaylor@tncsrv04:~]$ dig -x 2600:3c00::f03c:91ff:fe26:8849 83117 IN PTR

Thanks for the second set of eyes, because I obviously missed something.

Once upon a time, Grant Taylor via NANOG <> said:

I am having problems sending email to GMail from my new (< 2 weeks
old) Linode VPS.

May not be the case here, but I had an issue with my Linode and IPv6
email (not with though). If you just "request IPv6", you get
a single /128 out of a common /64. The problem is that most people
doing IPv6 anti-spam treat reputation on at least the /64, not
individual /128s.

You can request a /64 from Linode, no additional charge. I switched to
using my own /64, and I haven't had any issues since. I use Lynx to
look things up in Google sometimes, and was also periodically getting
blocked from that (with a captcha!). Since switching to my own /64, I
haven't had any issue there either.

After updating my SPF record per Gareth's recommendation, email now seems to be flowing to GMail properly.