SMTP Authentication when away from home

[#1]

Having difficulty sending with T'bird when away from home - only use it occasionally but the settings seem to change and I'm not convinced that the web info is kept up to date?

https://www.plus.net/help/email-guides/how-to-set-up-plusnet-email/

I know it needs to be authentication when not on home line but what used to work when away is now failing.

Which port should I use and which authentication etc? Doesn't seem to be working on K-9 mail on android but equally not used regularly for sending so cold have changed a while back.

Thanks,

[#2]

Do not confuse authentication with encryption.

Regardless of where you connect from, encryption is desirable - for SMTP

• Server relay.plus.net
• Port 587
• Encryption STARTTLS

When connected to the Plusnet network, you do not need the connection to be authenticated, but there is zero benefit in not doing so ... and when you are elsewhere, you will encounter issues as you describe if not authenticated.  Authentication should use the same user name and password as the incoming server using the "use the same as the incoming server" option or specifying them explicitly.

However, that is not the end of the matter, especially if you are connecting over a mobile network.  If the network address assigned to your mobile device has been abused by some prior user, then it might be blocked entirely from sending emails to Plusnet.  Email clients will report ANY connection error as a password failure, which is not helpful.  There are diagnostic tests you can run, but they are not so easy on a phone if do able at all.

If your configuration works over a Plusnet connection but not over mobile, is that in one specific location?

[#3]

I have my phone connecting okay via the mobile network. I have k-9 mail on android and blue mail and have checked my settings against those on T'bird on pc.

When using my laptop and the local wifi / network connection I'm getting problems and requests for password repeats. I've now found the error console and am seeing that actually it might be the IP reputation:

"Authentication failed: ...authentication rejected as source IP has a poor reputation"

So it appears it is something to do with the IP I'm issued / using. Is there any way of easily getting this reset as I believe this ought to be a good IP or do I have to tether my phone and use mobile data for sending which is a bit of a bore?

Thanks,

[#4]

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@LaurenceM wrote:

When using my laptop and the local wifi / network connection I'm getting problems and requests for password repeats. I've now found the error console and am seeing that actually it might be the IP reputation:

"Authentication failed: ...authentication rejected as source IP has a poor reputation"

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Is this when you are away from your HOME  connection?

[#5]

Yes when away from home and not using a plusnet connection - not away very often but when I am I seem to have problems which is just hassle.

[#6]

OK. You need to set authentication on your TB installation on your home computer, as I think @Townman has mentioned earlier.

[#7]

I've now set it and it works from my mobile network (with authentication) and if I tether my pc to my phone (on three network so no connection to plusnet so will need authentication) it works. If it is wifi to a different IP address it fails so it looks like it is the network related and reputation based.

[#8]

What/where are these 'different IP addresses'?

[#9]

One is from three mobile which works okay for sending.

The other is from a wifi connection (not plusnet) which will not send from either phone or pc despite settings being the same as those that will work with mobile data from phone and tether to pc which suggests that the settings are okay.

Thanks,

[#10]

I'm a  little confused here. The only time I'm aware that you are likely to get this kind of situation is when you are using a mobile connection which uses CGNAT, where the same IP can be allocated to numerous users and one/some of them use them for - shall we say - dodgy behaviour. Is this Wi-Fi location at a private home/business?

[#11]

Yes John,

This description is a tad confusing, probably not helped by email applications reporting every issue as a “password failure”.

If the bad IP address issue is correct, then some previous user has abused the IP address either by spam email or possibly too many password failures.

If this is on the mobile net work, set the device to aeroplane mode wait a few minutes and switch networking back on. That should get a new IP address.

If the issue is when connecting to Plusnet AND THERE IS NO VPN INVOLVED then if the user does not have a static IP address, turning off the router for 90 minutes should assure the allocation of a new IP address.

If there is a VPN involved, take the issue to the VPN provider - they need to tidy up the use of their VPN service.

[#12]

It is with pc and wifi connection to a large organisation site wifi that that gives the problem. I'm certainly not using a VPN can't comment for the organisation. Clearly I can't reset their connection. My SMTP login works fine when I do it from my phone (using K9 mail or Bluemail over mobile network and if I tether my pc to the mobile it connects correctly with T'bird too. It's when either uses the organisation wifi  connection. Thunderbird initially just reports password problems but if i look at the error console it reports "Authentication failed: ...authentication rejected as source IP has a poor reputation".

Of course there could have been someone else who has an infected pc that has caused this however I appear to be giving the correct information to log in as it works if the mobile connection is doing it.

I'm not away that often but it is a bore if it just doesn't work and I can't prove it out before going away of course as that is from a home connection via plusnet line.

[#13]

Ah a fuller description is most useful. “A large organisation site” will to all intents and purposes have similar characteristics to a VPN - lots of users appearing to use one IP address. It is evident that Plusnet’s services have experienced lots of failed attempts to access its services from that IP address. Now the IP address has been jailed you are not going to establish a connection even with valid credentials.

This is a good standard security practice.