smtp.plus.net not responding

[#1]

Same behaviour on WiFi and 4G.

I tried closing the mail app, hard reboot the phone - no change. 

Deleted and recreated the account (let's call it PN1), checked all the settings were the same as previously, and it verified the account on creation but mail fetch failed in the same way (mail server imap.plus.net is not responding).

Created yet another account (PN2) and it worked!  Had another look at this account's details and realised I'd let it default to SSL on, port 993 for imap.  So I went back to account PN1 and changed that to use SSL & port 993 and that worked as well.  To add the final bizarre topping to the cake I then changed account PN1 back to SSL off & port 143 and it continued to work whereas it hadn't before I switched SSL on and off again  

So it is now working but I'm none the wiser as to why. I am wiser with respect to the fact that you can't use ping or traceroute to verify routing to PN's mail servers.

Yet another bum steer was creating a PN account on my (ancient, stuck on iOS10.3.3) iPad using all the correct settings - it just complains that the username or password is invalid when it tries to verify the account   Not a problem 'cos I only use it for browsing but it served to cloud things further.

[#2]

Hi Mike,

There are indeed some oddities with iOS email on iDevices.  It is worth doing a Google search for them.  I have seen a few in my time.  I know that I have repeatedly corrected the password on an account only for it to still fail.  I have then (similar to yourseld) created a clone, which has worked fine ... and then gone to the origional and found resetting the account details has made it too work without issue.

I have also seen issue when accounts have been deleyed ... their SMTP settings get left on other account's optional SMTP server settings ... I suspect that such contributes to internal account configuration corruptions.  The means by which these might be removed is a bit obscure.  I did Google that once but cannot recall the answer.

I have a Mk2 iPad on iOS 9 which continues to work fine, so it is not specifically an iOS 10 issue!

[#3]

Thanks @Townman , I've marked you post which included the suggestion of deleting & recreating the account as the solution, which it pretty much was with the addition of some irrational faffing about.