Email, Three (3) and Spamhaus

[philmossuk]

I'm using an unlocked CPE Pro, 370 variation, on Three. I have a problem getting emails to some recipients who use spamhaus.net filtering. The bounce-back message reads

"An error occurred while sending mail. The mail server responded:
554 5.7.1 Service unavailable; Client host [92.40.190.0] blocked using sbl.spamhaus.org; https://www.spamhaus.org/sbl/query/SBLCSS.
Please check the message recipient "*.*@nhs.net" and try again"

Further investigation reveals that Three themselves have instructed Spamhaus to block some of their addresses.

Before I begin the long and no doubt fruitless battle with Three has anyone got any workaround ideas, please.

 

[Buggerlugz]

Try the Windscibe VPN (think you get a free 10Gb a month) and just fire it up before sending emails.

 

[sheephouse]

Do you run your own smtp mail server? If you use your ISP's server the mail will be seen as originating from their address rather than a Three address, and should be accepted. Generally, mail originating from a dynamic address is likely to be spam, and such addresses will be included in many block lists.

 

[Lucian]

Get in touch with your email provider and ask them if they can hide your IP address, explain the situation.
E.g. with Postfix email server it can be done like this:

Remove/hide client sender ip from postfix?

I'm trying to hide the client IP from emails sent from postfix. here is an example of what I mean: Received: from mail.[removed].com (adsl-75-37-61-254.dsl.frs2ca.sbcglobal.net [75.37.61.254]) (

serverfault.com

 

[bonehead999]

Just as an aside: You haven't obfuscated the email address you are sending to correctly. The actual recipient address is still present in the mailto of the href attribute. Please edit your post to protect the poor guy.

 

[philmossuk]

Thanks everyone for the response. I need to add further information..
1. I am dabbling with Three, my main system remains landline based broadband from Plusnet, using Fasthosts to provide domain hosting and email including smtp.

2. I switch every now and again over to Three via changing WiFi network. Reason, my landline based bandwidth is low and Three are about to bring 5g to my area, indeed are already undertaking preliminary works, meaning every now and again the 5g light goes on for periods of up to an hour. It is only with Three that I have this Spamhaus issu.

3. I never change the SMTP from Fasthosts. Maybe without telling me or showing a sign it must be somehow be changing to use Three as the SMTP?

Now, I’m sure there are people who know a lot more than me but I can’t see Fasthosts as the culprit and solution here.

I am guessing that either within the Three sim or APN (I’ve tried both 3.co and 3Internet APN) setup something is hijacking my smtp..

Again thoughts appreciated..

 

[Lucian]

You should get in touch with Fasthosts and explain the problem, ask them to hide your sending IP as per the article I linked.

 

[philmossuk]

Update: Contacted Fasthosts and no go, they can't/will not do anything. Having seen issues elsewhere where 3 have setup 5g in an area, but are not yet officially adopting it, I'm beginning to wonder if they are blocking off "Client host [92.40.190.0]" until the 5g implementation is officially complete.

ps thinking about it there are potentially legal and ethical reasons why Fasthosts might be unhappy with hiding client sender as they aren't like vpn with an overseas operating base.

 

[Lucian]

Time to go shopping maybe?

Re implications, don't think there are any. The opposite could be argued, see GDPR etc.

 

[philmossuk]

SOLUTIONS.

1. Applying a VPN worked but the speed overhead was very high

2. Using the free 1.1.1.1 for DNS worked and with a much lower speed overhead (approx 10% meaning I'm still getting 350MBPS via ethernet link to 112-370 Router.)

3, Haven't fully confirmed this but I suspect it may have solved itself i.e. Three registered offending addresses themselves and at the time of my problems the local Tower was undergoing the change to 5g & could be they blocked of the addresses to stop people like me jumping in sooner than they wished. OR Someone else complained to Three & they withdrew the Spamhaus blockage.

My tower/area still doesn't show on the Three 5g coverage maps.

Thanks for the efforts of contributors, and hope these solutions may help others.

 

[Lucian]

Point 2 couldn't have made a difference.. Also just by using another DNS couldn't have affected your uplink speed.

It was prolly point 3 that solved it for you.