The issues centre on the outgoing mail server it seems, both accounts unable to be verified.

Their email / passwords are correctly entered but not being recognised.

I have other accounts with the same Zoho config detail that are working fine with Apple Mail so this is strange.

These other accounts are using zoho.com (not zoho.eu) - i've tried both .com and .eu for these non-working accounts but it makes no difference.

I also posted my issue on this thread and was informed the issue has been resolved - but not for me.

Please help me to resolve this!