Cannot get ZOHO POP3 to fetch a few messages, which have been added "out of their turn" to the INBOX that is being POPped

Cannot get ZOHO POP3 to fetch a few messages, which have been added "out of their turn" to the INBOX that is being POPped

I have one main ZOHO account, under which I have set up a few POP3-accounts, since ZOHO is really such a brilliant environment.

There recently was trouble with the home accounts (non-ZOHO) of a couple of the POP3"feeds". The result was that I had to merge one home account (non-Zoho) with the other, consequently also merging their Zoho-representations. All went rather brilliantly.

However, upon resuming normal duty with each home account (non-Zoho) receiving its mail and having them POPped by my Zoho account into each their sub-account representation, I found that a couple of handfulls of mails refuse to be copied to their Zoho-subaccount-destination. These stubborn mails are some, which I MUST keep in their original home accounts, i.e. they were originally merged and subsequently had their original status re-surrected and were "retro-merged".. But they now REFUSE to be copied to Zoho-subaccounts, which I reallt think they should ..

I have checked the latter for instances of the same mails already being downloaded somewhere. Everthing is cleared now, also from the Trash.

Reasons? Suggestions?