Emails send from rails with O365 being rejected as spam - ruby-on-rails

Question

I have a Rails 5 app deployed on Heroku. I'm using devise for email and have setup everything correctly to send password reset emails. This works perfectly in my dev environment. However, when I send from production I get an error in my 0365 inbox that says:
Generating server: CO2PR13MB0140.namprd13.prod.outlook.com
myemail#gmail.com
Remote Server returned '550 5.7.708 Service unavailable. Access denied, traffic
not accepted from this IP. For more information please go to
http://go.microsoft.com/fwlink/?LinkId=526653 AS(8561)
[CO2PR13MB0124.namprd13.prod.outlook.com]'
Original message headers:
Received: from CO2PR13MB0140.namprd13.prod.outlook.com
([fe80::c872:9c6:9d6a:8b3]) by CO2PR13MB0140.namprd13.prod.outlook.com
([fe80::c872:9c6:9d6a:8b3%4]) with mapi id 15.20.1339.019; Wed, 14 Nov 2018
02:42:20 +0000
MIME-Version: 1.0
Content-Type: text/plain
Date: Wed, 14 Nov 2018 02:42:20 +0000
Message-ID:
<5beb8b87e888a_42b06292aba70609bd#01184e4c-2116-478b-a773-fcc26ac206aa.mail>
Subject: Reset password instructions
In looking into this, and talking to support, it appears that the it's being rejected because a third party server is (my app on Heroku I'm assuming) is trying to send out the email with 0365 settings.
Here are my development.rb settings that work perfectly:
# Don't care if the mailer can't send.
config.action_mailer.raise_delivery_errors = true
config.action_mailer.perform_caching = true
config.action_mailer.default_url_options = { :host => 'localhost:3000' }
config.action_mailer.delivery_method = :smtp
config.action_mailer.smtp_settings = {
:address => 'smtp.office365.com',
:port => '587',
:authentication => :login,
:user_name => ENV['365_USERNAME'],
:password => ENV['365_PASSWORD'],
:domain => 'mysite.com',
:enable_starttls_auto => true
}
Here are my production.rb settings that cause O365 to reject the email. I've tried playing with these quite a bit. And I've ensured that the "from" email matches the login email. i.e. I'm not trying to send from no-reply#mysite.com or similar.
config.action_mailer.raise_delivery_errors = true
config.action_mailer.perform_caching = false
config.action_mailer.default_url_options = { :host => 'www.mysite.com' }
config.action_mailer.delivery_method = :smtp
config.action_mailer.smtp_settings = {
:address => 'smtp.office365.com',
:port => '587',
:authentication => :login,
:user_name => ENV['365_USERNAME'],
:password => ENV['365_PASSWORD'],
:domain => 'mysite.com',
:enable_starttls_auto => true
}
From discussions with support. I may need to add an SPF TXT record to allow emails to be sent from a remote server. The problem is, I have no idea what to add to the SPF record. My current spf record is:
v=spf1 include:spf.protection.outlook.com -all

Answer 1

Their response just says they have blacklisted your IP, so it’s not down to your message content.
If you are sending from Heroku, you may need to list them in your SPF as well. Also ensure that your host name resolves backwards as well as forwards - that should be possible in Heroku’s control panel.
Once you’ve done that, check your SPF record gives a pass to your message source using kitterman.com or mxtoolbox testing services.
O365’s spam filter and blocking policy is pretty bad anyway, however I have had success in asking their support to remove blocks, though you need to persevere because they reject all such requests by default. This is poor service, but it’s still far better than you will get from gmail.