IMAP works on some devices not other with exact same settings

[#1]

Hello folks - hope you can help me with a niggling little problem - I have my Plusnet mail (IMAP) set up on a Mac mini, older MacBook Pro, and iPad and an iPhone. It works though there is little traffic these days. I recently got a new MacBook Pro which, as ids the way these days, did most of the setup with little intervention from me. My Plusnet mail just will not work - the 'connection doctor' tells me the SMTP side of things is OK but the IMAP connection fails (account not recognised). I checked and double checked all the settings (including username, password, port 143, etc.) and I cannot get it working. I am puzzled so any help appreciated - I mean why work on some devices but not others? is there something about my new Macbook that is different? 

All Mac devices are apparently on the same level of software - the MacBook is a 2010 model and the Mac mini a 2012 - the new one is the 2017 update.

cheers

Paul

[#2]

Is there any chance you can attach a screenshot of the settings?

[#3]

hope this works 😉

[#4]

Those settings appear OK unless something is hidden within Advanced IMAP settings.

Could you try entering the following telnet command at a command prompt (is that in a Terminal window on a Mac?)

telnet imap.plus.net 143

* OK [CAPABILITY IMAP4rev1 UIDPLUS CHILDREN NAMESPACE THREAD=ORDEREDSUBJECT
 THREAD=REFERENCES SORT QUOTA IDLE ACL ACL2=UNION] Courier-IMAP ready.
 Copyright 1998-2011 Double Precision, Inc. See COPYING for distribution information.

Hopefully the server will respond with the welcome message shown.

Now type

01 LOGIN username password
(substituting your own username and password, of course).
You should get a response
01 OK LOGIN Ok.
Follow this with
02 LOGOUT
to disconnect

If that works it confirms you can connect, implying the problem with the email client is settings-related.

[#5]

thanks for the response - yes terminal gives you a command prompt.

the first attachment is the 'advanced' settings 

Terminal didn't like the telnet command but the Mail Connection Doctor appears to do a similar thing. 2nd attachment is the log file that seems to indicate that what you are requesting has happened. 

Thing is this account works on the other devices so it is something local to the new MacBook - if only I knew what it was. 

[#6]

Only one file was attached, the connection log?

That shows connection and logout were successful, but omits the LOGIN step. That would have confirmed username and password were not being mangled routinely by the new computer.

[#7]

Apologies for going offline with this - I'm juggling several things at once here and keeping an eye on the weather!

First I have attached the other screenshot - just to show what lies behind the advanced email settings. Nothing wrong or different there to my untrained eye. 

Second - the mystery of the failing telnet command - Apple have removed telnet from the latest OS so that route isn't open. 

Third - I have tried an alternative method of logging in to the imap.plus.net server (SSH) but frankly it is getting a bit beyond my comfort zone so more digging about required  

I will continue to dig around - specifically looking at logs on the 2 Macs where this account works. Probably worth me looking at the Firewall settings too 

Thanks for the help so far though - much appreciated 

Moderator's note by Mike (Mav): Personal information removed from attachment in a public forum.

[#8]

Looking at that screen shot, I rather suspect that it is MAC / Apple forcing "secure" logon (SSL / TTL) which Plusnet does not support.  Try ticking the allow "insecure" logon box.

[#9]

@Paulgarb Yes ticking the "Allow insecure login" box will hopefully fix the problem.

With regard to telnet, have Apple completely removed it from the computer or is enabling it still an option? Instructions for doing the latter are readily available if they will work.

Unless there is an option to use SSH without SSL (ie in telnet mode) login to imap.plus.net will not work because SSL/TLS connections are not yet supported.

[#10]

Thanks but have tried ticking the box - no impact at all 

[#11]

As above - tried it and it didn’t work. 

As for telnet it is, as of High Sierra, gone from the operating system. Some reports of copying it over from an old setup but I’m not that bothered. 

As the mail account works happily on my other Macs I had written it off as a hardware/software combination thing until.......

Well I won’t bore you too much but my backup product (Carbon Copy Cloner) allows email notifications of any errors - I set it up to use the PlusNet account and it successfully sent a test mail (bypassing Apple Mail to do so). 

So now I’m confused and not a little disappointed I can’t fathom the cause. If all else fails I’ll just delete the account altogether - too much effort spent already on a rarely used mail account. 

Thanks again 

[#12]

Excuse the question, but you did click OK after ticking the box? There doesn't appear to be an equivalent OK/Apply/Done button if a change was made on the account page.

Does exiting the app and restarting after making the change make any difference?

[#13]

I assume the Cloner app only sends emails, and my understanding is you have that working in Apple Mail?

In fact if the problem with IMAP is security related, why are they less fussy with SMTP? The Automatically manage connection settings option has been set for SMTP; what shows if you turn that off? Is it not bothering with authentication at all (which will work from a Plusnet connection)?

[#14]

It is a fair question & yes BUT because the change (or attempt at it) fails the setting doesn’t ‘stick’ it resets itself every time. 

I have also tried every variation of exiting app & restarting I can think of - and my background is in IT so switch it off & on again is the first thing I try. I may be a Mac person now but I had years of horrendous problems with PCs at home & work that haunt me still 😉 

[#15]

You will see on yesterday’s screenshot that the ‘manage automatically’ bosx is deselected, what you get is port number, authentication choice, etc. 

As to the Cloner app - I have to define the email credentials within the app and it bypasses Apple Mail. My issue is that Apple Mail on the one machine is refusing to play ball. But like I said it really isn’t worth this level of effort now.