Odd behaviours of late

[#1]

First

I sent emails to persons, whose names are in my address book. These persons have Plusnet email accounts, one in his private capacity, the other as an officer in a society. Both failed with a long message about ID, MX etc etc, ( Sorry I did not copy, but I was struggling with a supermarket site */437

Second

My wife has her own account with luzern.plus.com, so I am aware of them as they enter her inbox. Several recently have not appeared, but her IPad they were waiting for her to read.

Where would you suggest the problems emanate from; Plusnet or my email client, Thunderbird.

Please tell me of any solutions. if Plusnet is the culprit.

[#2]

The detail of the error message might help a little...

[#3]

I've tried to resend to one, and here is the result impersonalised

<nnn@domain.plus.net> recipient rejected - domain has no delivery address (DNS MX or A record).
Please check the message recipient "nnn@domain.plus.neet" and try again.

[#4]

'nnn@domain.plus.neet' ?

[#5]

OOps  and double oops @jab1 , it should be neither net or neat, but com, of course. 

[#6]

@Luzern, so just to make sure, you were sending it to the nnn@domain.plus.com address and it was that address that was actually in the error message?

My first though of where to check is that they both still have those email addresses.  The error message is basically saying that domain.plus.com (if the answer to my above question is yes), so (unless the error is totally wrong, which isn't impossible), either those two users have been deleted (so domain.plus.com has been removed from the DNS), or the email system has had issues looking up the domains in DNS.  The first is something that you should be able to do, and would be the most likely I think.  The second would need someone at Plusnet to dig through the logs (or whoever's systems actually generated the error if it isn't Plusnet).

[#7]

Mea culpa maxima.😥 Goodness knows why, but I managed to box and cox some of the addresses in the book.

Now what could be the second problem, please? I hope you are still willing to help!

[#8]

@Townman @pjmarsh 

I had decided  to uninstall my email client 'just in case' it was part of the problem. As part of pre-preparation I had to reboot so closed system overnight. This morning all the missing emails were showing.😂

Have you got ideas how all this hoo hah could have come about?

[#9 · Accepted solution]

Win10?

My guess would be that the windows coms stack had become confused. Sometimes I find my machine loses It’s WiFi connection (Other devices are absolutely fine) and disconnecting and reconnecting (or restarting) sorts out a few inexplicable issues.

[#10]

@Townman  Yes, Win 10 H&S. I'll try to remember rebooting, as a problem solver.

Thanks.

[#11]

Moderator's note by Mike (Mav): The fix has been changed to @Townman  as per message #9..