Skip to main content

g suite - Configuring SPF, DKIM, Reverse DNS for VPS sending email through Google Apps SMTP servers



Today we realized that all of our emails being sent to email addresses of the type @corporatedomain.com were getting rejected. I don't know who is hosting the email for corporatedomain.com. I don't think that should matter. Anyway, the error we were getting was 



Technical details of permanent failure:
Google tried to deliver your message, but it was rejected by the server for the recipient domain example.com by mail.example.com. [yyy.yyy.yyy.230].

The error that the other server returned was:
550 5.7.1 Command rejected




  • We have a Google Apps account for mydomain.com. The DNS for mydomain.com had the SPF record v=spf1 mx include:spf.mailjet.com -all.

  • We are using the Google Apps SMTP server to send transactional emails from with my app. We am using the mailjet account to send bulk marketing emails.

  • Since the mail for this domain is handled by Google Apps, the MX records all point to the default Google app ones.

  • My VPS has two public ip addresses. I don't have an SMTP server installed on my VPS. I send emails from within my VPS using the Google Apps SMTP server ONLY.

  • Only the emails sent via the Google App SMTP server were getting blocked. The Mailjet ones delivered fine.



Given the above usage pattern & VPS environment setup, I assumed the SPF would checkout properly (the MX records point to Google and I am using their SMTP servers to send email).




Googling the error really didn't lead to anything. Eventually I tried carpet bombing the issue by including whatever I could think of in the SPF. And now it works. Cool! The spf entry now reads



v=spf1 include:_spf.google.com include:spf.mailjet.com ip4:xxx.xxx.xxx.143 ip4:xxx.xxx.xxx.144 mx ~all


But I am not sure WHY it works. I really DONT want to do a trial & error to find the bare minimum settings that work for the recipients domain. There must be a spec for these things, right? After all, all emails were/are getting delivered to all users (not with emails belonging to corporatedomain.com).



I have a suspicion that in the current SPF entry, the ip4 mechanisms as well as the mx one are not needed. Google documentation recommends using include:_spf.google.com instead of mx. Also, this one ends with less restrictive ~all. The old SPF ended with the highly restrictive -all. Can someone confirm what the ideal SPF record should be for my use case?




Side note: I have now configured DKIM authentication for mydomain.com. I don't know if I need to setup Reverse Dns. I don't think I do, as I am not "sending" the email, the Google Apps SMTP server is. Please correct me if I am wrong.


Answer



The include:_spf.google.com you eventually added is likely the critical bit here. It flags Google's servers as being legitimate senders of mail on your behalf.


Comments

Post a Comment

Popular posts from this blog

linux - iDRAC6 Virtual Media native library cannot be loaded

When attempting to mount Virtual Media on a iDRAC6 IP KVM session I get the following error: I'm using Ubuntu 9.04 and: $ javaws -version Java(TM) Web Start 1.6.0_16 $ uname -a Linux aud22419-linux 2.6.28-15-generic #51-Ubuntu SMP Mon Aug 31 13:39:06 UTC 2009 x86_64 GNU/Linux $ firefox -version Mozilla Firefox 3.0.14, Copyright (c) 1998 - 2009 mozilla.org On Windows + IE it (unsurprisingly) works. I've just gotten off the phone with the Dell tech support and I was told it is known to work on Linux + Firefox, albeit Ubuntu is not supported (by Dell, that is). Has anyone out there managed to mount virtual media in the same scenario?
Post a Comment
Read more

ubuntu - Monitoring CPU, Mem, disk, on a single server

I've been looking for a simple starter solution for monitoring my [currently] single server hosted solution. Other than Nagios and similar, are there other good (simple) solutions people are using? Answer Everything depends on what you want. For example Munin is very simple, you can install and configure it in less then 10 minutes (on one server), it can sends alarms, make graphs from monitoring cpu, mem. apache connections, eaccellerator, disk io and many many more (it has many plugins). But if you are planning in future get some more machines, munin may not be enough. For example in munin you cant monitor state of individual processes, can't monitor changes in files (for security purpose). So if you wanna only see what is the utilization of basics parameters on your server and don't plan to buy some more servers Munin is what you are looking for, but if you wanna be alarmed when some of your service is down, take more control on what is happeninig on...
Post a Comment
Read more

hp proliant - Smart Array P822 with HBA Mode?

We get an HP DL360 G8 with an Smart Array P822 controller. On that controller will come a HP StorageWorks D2700 . Does anybody know, that it is possible to run the Smart Array P822 in HBA mode? I found only information about the P410i, who can run HBA. If this is not supported, what you think about the LSI 9207-8e controller? Will this fit good in that setup? The Hardware we get is used but all original from HP. The StorageWorks has 25 x 900 GB SAS 10K disks. Because the disks are not new I would like to use only 22 for raid6, and the rest for spare (I need to see if the disk count is optimal or not for zfs). It would be nice if I'm not stick to SAS in future. As OS I would like to install debian stretch with zfs 0.71 as file system and software raid. I have see that hp has an page for debian to. I would like to use hba mode because it is recommend, that zfs know at most as possible about the disk, and I'm independent from the raid controller. For us zfs have many benefits, ...
Post a Comment
Read more