email migration complete but unable to log into mailboxes. How to add Domain

[#1]

Hi,
This may be a bit more of a complicated one due to having transferred my domain i had hosted with force9 out a couple of years ago.  I had thought that the email service was going to be cancelled then but it turned out it was new customers only who wouldn't get a mailbox.  Anyway, my emails continued to work as I had the DNS MX setup on GoDaddy to point to the correct server and my domain was still usable on the mailboxes.  This however has caused issues since the migration to Greenby.  I can see all the mailboxes on the dashboard and view them from the dashboard but can't log on via the new greenby webmail site.
I also can't send emails out with the domain name , this is due to the domain not being hosted by force9 during the migration.
So the questions are:  How do I link my domain back into Greenby and why can't i log into the individual mailboxes?  I also can't log in via a mobile email client like Outlook but if I can give a way to my family to log into the webmail then at least they can read their emails.  Anyone had any similar issues?  Thanks

[#2]

@eladhubb 

Anyway, my emails continued to work as I had the DNS MX setup on GoDaddy to point to the correct server and my domain was still usable on the mailboxes.

It should not have been possible for you domain email to still be handled by the force9 server once the domain had been moved away. I suspect there was an error removing your domain from the force9 account and the migration may have rectified it!

I can see all the mailboxes on the dashboard and view them from the dashboard but can't log on via the new greenby webmail site.

You should be able to login using the force9 usernames but you won't be able to use the domain email addresses. 

I also can't send emails out with the domain name , this is due to the domain not being hosted by force9 during the migration.

That's to be expected given above

So the questions are:  How do I link my domain back into Greenby

ICBW but I'm not even sure that's possible... I suspect you will need to find another hosting for your domain email

[#3]

Thanks.
What I've noticed is that all the mailboxes had their passwords reset to the main account password.  Once I reset these to a unique one for each mailbox I could log into the webmail.greenby.com site for each mailbox.  

Accessing the mailboxes via the dashboard still works with the new passwords.

I've reset the mail client IMAP account details using the settings from the Grennby dashboard and used the new passwords and non domain email address and everything seems to be coming through ok. 

I just need the domain linked again. The chatbot at Greenby seems to state I can move a domain over but when i wait to speak to an actual agent they don't seem to appear so i'm not impressed by the support at the moment.  

[#4]

@eladhubb 

I've reset the mail client IMAP account details using the settings from the Grennby dashboard

I hope you haven't, they're wrong if they are the same as I see on a migrated test account!, they are the unencrypted settings. Its been reported to the business.

You should use IMAP port 993 with SSL encryption and SMTP port 587 using STARTTLS