message of "enter at least one recipient" on roundcube, when i have my mail server ok

Solution 1:

This is caused by the Arabic numerals in the last label.

three virtual domains domain1.al1,domain2.al1, and final.fi1

Roundcube performs some preliminary validation on entered emails, throwing out domains where the last label contains numbers.

In ICANN maintained TLDs such would only occur in IDN form, such as .xn--p1ai representing .рф.

The purpose of rejecting some possibly-invalid domains is usually preventing unintended parsing of a recipient name as a recipient address (or vice versa).

There is a simple change scheduled for a future release that relaxes the domain validation so it would match your unusual domains as well.

You would still be well advised to only use domains that are guaranteed not to be assigned to a third party eventually. That is, a subdomain of a domain you own (or at the very least, a domain reserved for such purposes).