Help, can't read emails and user doesn't exist! Greenby migration? Something else?

[#1]

My wife has a mailbox on our plusnet account and accesses Thunderbird or uses the mail app on her phone to get her emails. As of yesterday morning, her password is not recognized and she can not receive emails, however she can still send them,  presumably because no password is needed for this. Even more worryingly, I can not send a mail to her from another account as it gets bounced back Undelivered Mail Returned to Sender,. This is the mail system at host mail.enmail.co

Further in the mail it mentions that the user doesn't exist and mentions a host local-dovecot.enmail

I assume she's transferred to Greenby but unsure how to resolve. Do I need to change a setting in her email client?

She's getting a bit desperate now as it's been 24 hours!

[#2]

Check the Greenby and / or Plusnet email portals to see if the address you are trying to access exists.

Be sure to use the real email address as the Username, don't use <account>+<name> or an Alias.

Moving to Greenby SMTP servers must be configured with a Username ( email address ) & Password
and will only be permitted to send using an email address or Alias that corresponds to your account.

[#3 · Accepted solution]

Thanks for your prompt reply. Yes I went to https://www.plus.net/my.html and her email address exists. At Greenby https://greenby.com I get Account details not recognised, please try again.  I went through the process of contacting Plusnet on 0330 123 9123 who helped me complete the migration. I found that her email address and none of our others was marked as disabled at Greenby. 

That was the end of Plusnet's support but I'm very grateful to them. I checked her email on Thunderbird and found lots of undeliverable scam messages over the last few hours. I suspect her email was compromised by a virus generating lots of spam emails so Greenby disabled it. 

Just a theory but I'll do a full virus scan. 

Thanks again.

[#4]

One learning point was that to log onto Greenby, I had to use my Plusnet username and password and not my wife's email address and her password. Hope this helps anyone else trying to log onto Greenby.

[#5]

@simonides 

The portal at greenby.com needs the account name and password, as it controls (and has access to) all mailboxes.

Logging directly on to webmail.greenby.com for a mailbox needs the mailbox email address and password.

[#6]

I keep reading comments about sign in details

Sorry I may be a bit thick but 

1  Full email address

2 Username

These are TWO completely different things

using the wrong one will result in Login Failed

[#7]

Yes, confusing isn't it? The portal at Greenby.com asks for Username or Email Address but they mean the Plusnet account's username. I tried my wife's email address with no luck. Sorted now!

By way of update, the account was again disabled a short time later but I reenabled it, changed the password and no problems since then. I should have changed the password at the outset. Another learning point.

I didn't detect any viruses on her computer despite doing a full scan with Bitdefender which is usually quite thorough.

[#8]

Good clarification, thanks Mavison!