535 ...authentication rejected as source IP has a poor reputation

[#1]

I am using an Android phone on the three network. Last night i sent some emails ok, today I can't. This seems to happen on and off. When the emails don't go, i get an error 535 and my ip has a poor reputation. I think Three might have something to say about that! I have restarted the phone and gone in and our off airplane mode to try and get another IP address so I can send some emails but no joy. Why can't you just use encryption instead of plain passwords and ip address checking? My phone thinks it's ip address is currently 100.98.161.48
Thanks - Bob

[#2]

@bobmanekshaw I think you will find that is a Three IP range - it certainly does not appear to be a PN one from my long experience.

What does your computer/laptop report as its IP?

[#3]

I am camping at the moment and only have my phone. There is no wifi either. I can read & delete emails but not send them today but i could yesterday from the same spot. Have double checked the settings as well as the password on the email app. My phone is on the three network not PN.

[#4]

In that case, you are definitely not on a Plusnet IP, so your complaint needs to be addressed to Three.

[#5]

But its your email server causing the problem .... Your server prevents my login to send emails on some of the ip addresses that Three provide me. As PN are using ip address filtering to prevent spam surely the problem is your filter. All my other email accounts still work perfectly but this is my main one and the only one that doesn't have ssl either.

[#6]

Point one - I am not a PN representative, merely one customer trying to help another.

Point two - If the Plusnet mailserver has identified that source IP as 'bad', there will be a good reason for it. Maybe your other email accounts are not as selective as to which IPs they will allow to send from.

Point three - SSL is available on Plusnet.

[#7]

Ok Jab1 - Apreciate the help and that you are a community member and not PN rep. I should have phrased my first sentence better and so i apologise.

I do have to point out however that when i checked the imap instructions produced by PN they say there is no SSL - https://www.plus.net/help/email-guides/how-to-set-up-plusnet-email/

Because I started with freenetname who became madasafish and now plusnet, my email passwords are limited to 8 alpha characters so sending them plain text isn't a great option these days. I have just tried enabling ssl and I get the same error. Thank you for the advice there but it has not resolved my issue.

As for whether the other email systems are more or less fussy, three of them are corporate business systems and the fourth is gmail. I can't make a claim as to who has the best security but as a PN and a Three customer for many years now - both of whom are reputable service providers I do find it odd that I can send emails one day and not the next.

So how do I escalate my issue to PN?
Thanks - Bob

[#8]

OK Bob - no problem.

The email setup instructions have not been updated - although secure send/receive has been available for 9/10 months - have a read through This post  for guidance.

There is no real escalation route for your issue - the IP 'reputation' is decided automatically (as I understand it) by the servers, based on built-in algorithms.

[#9]

@bobmanekshaw I'm afraid using ssl will not solve your ip reputation problem, Plusnet use the Cloudmark anti  spam system and if its decided that the ip you're sending from has a poor reputation then it will not permit sending from that ip. It's a problem with mobile networks where the ip addresses are reallocated regularly. If the previous user has behaved badly then the ip reputation will be affected. All you can do disconnect and reconnect and hope that the new ip has a better reputation.

Ssl is available though, as @jab1  says, although the guide has not been updated.

That at least will solve the problem of sending passwords in clear text

[#10]

@MisterW, just to check I've understood correctly, are you saying that you cannot send email using Plusnet's smtp server with an authenticated account if Cloudmark thinks your IP address has a poor reputation?

I'd not be surprised at a smtp server rejecting incoming mail from an address with a poor reputation, but surely it should always accept an authenticated connection?

[#11]

Thank you @jab1 and @MisterW  - I am now home and off course my emails now send OK now that I am on my Wifi connection. As far as I can tell the SSL settings are now enabled on my email app so that is a big step forward.

@corringham - you are correct - when I use 4G on my Samsung S8 phone to access my email on PN IMAP/SMTP servers I get the 535 error with or with SSL being used as @MisterW pointed out.  It's been happening on and off for a few months now but I have not been able to track the cause of the problem till now and with lockdown I haven't been using 4G that often.

I have had a look at the Cloudmark website and there seems to be a way of reporting a problem but I have no idea of how long it will take to resolve. I am very surprised that PN do not have a way of fixing it as they buy in the service and presumably have a support contract.  I appreciate that PAYG mobile phones are frequently used by spammers but I can't be the only PN customer having this kind of issue surely?

[#12]

I just used whatismyipaddress.com with the wifi off and my IP address is being reported as 92.40.184.0 and I still get the 535 message. Turn the Wifi on and my IP address becomes 209.93.53.151 and I can send my email.

[#13]

just to check I've understood correctly, are you saying that you cannot send email using Plusnet's smtp server with an authenticated account if Cloudmark thinks your IP address has a poor reputation?

@corringham  I may be wrong but that is my understanding. I've seen the problem myself when on mobile networks and I've always used authentication albeit not ssl until recently. 

I'd not be surprised at a smtp server rejecting incoming mail from an address with a poor reputation, but surely it should always accept an authenticated connection?

You would think so but from my experience the poor reputation check takes priority over any authentication.

Given that, my suspicion is that ssl will make no difference although I've not been able to prove that but it looks like @bobmanekshaw has

[#14]

I contacted cloudmark who gave me a link to reset ip addresses

http://csi.cloudmark.com/reset-request

But when i entered my ip address that is being flagged, I got the attached message saying its not black listed by them. (Well it would be attached but I cant see how to). By the way, i have a new ip address again this morning so that is three addresses that fail.

Where do I go now? Any thoughts?

[#15]

OK, if Plusnet's SMTP servers reject authenticated connections due to Cloudmark's reputation rating, then they are configured wrongly.

Couldmark's ratings are supposed to be used to allow mail from mail servers with poor reputations. The whole point of an ISP providing an outgoing relay is to allow users to send mails from the ISP's server, which hopefully will have a good reputation. If you can't connect to the ISP's server then it is useless.

I'm glad I've been running my own servers for years, so avoid this type of problem.