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Jeremie
Jeremie

Reputation: 1307

prevent emails from being flagged as SPAM - SPF configuration

Our business emails are often considered as spam. We are using gandi.net mails at the moment and send emails from our own mail clients using gandi smtp servers.

I've checked a few websites to test our email adresses for spam. I got the following report on one of them: SPAM Test It offers me to add some SPF configuration and sign the message with DKIM.

Regarding SPF, I am offered to add a SPF record using the source server (which is the gandi mail relay server relay3-d.mail.gandi.net).

offered improvement with SPF config Problem is, there are many mail relay servers, and whenever I send a mail, i get one of those as the source server. They seem to be on the same IP range:

enter image description here

So what am I supposed to do? add a spf record for each relay server? like 

v=spf1 a mx ip4:217.70.183.195 ~all

or maybe I can use the hostname for more readability?

v=spf1 mx a:relay3-d.mail.gandi.net ~all

Am I supposed to add the IP Range 217.70.183.193-217.70.183.201 ? (got the IPs belows from https://www.ipaddressguide.com/cidr#range )

v=spf1 a mx ip4:217.70.183.193/32 ~all
v=spf1 a mx ip4:217.70.183.194/31 ~all
v=spf1 a mx ip4:217.70.183.196/30 ~all
v=spf1 a mx ip4:217.70.183.200/31 ~all

I am a bit concerned about screwing up our DNS configuration while doing that so please advise! I made a few changes on the DNS configuration, then I got a SPF check error on one of those spam check tools online so I reverted everything until I get more feedback.

Upvotes: 0

Views: 1298

Answers (1)

Synchro
Synchro

Reputation: 37810

This is exactly the purpose of include directives in SPF. You have no way of knowing what their pool of mail servers is, and it may change frequently; Include means that maintaining that list remains gandi's problem, not yours.

Their SPF support page (why didn't you look there before asking here?) says you should add include:_mailcust.gandi.net, and that record covers some large IP ranges, including those you've mentioned.

Upvotes: 2

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