Hi…
After upgrading on BETA RC1, I have found another problem.
STATIC DNS - I translate my own static DNS entry for smtp server into my ISP SMTP IP adress.
On 2.9.xx I have no problem, but on v3 RC1 I have problem to sending my mails. SMTP server unreacheable 
Probably you have problem with the script syntax, that is translating dns-name,
as I do not have any problems to send e-mail from 3.0rc1 router (when correct configuration is used).
No no…
This problem appeared after upgrading from 2.9.x to RC1.
I try to downgrade…
What kind of problem with 3.0rc2 ? what exactly does not work for you ?
In /ip dns static>
Flags: D - dynamic, X - disabled
0 smtp.tynec.net xx.xx.xx.xx 40m
I am translating static DNS adress into IP adress because I have not got my own smtp server.
When someone use SMTP.TYNEC.NET in our network it will translate smtp.tynec.net into smtp.xx.xx.xx.xx.cz
Do you understand?
It is universal when I change my ISP, I only change static DNS entry on my GW and all my customers still use in email client smtp.tynec.net.
For exaple:
I change ISP from ISP XX TO ISP YY.
I only change static entry on my GW:
Flags: D - dynamic, X - disabled
0 smtp.tynec.net yy.yy.yy.yy 40m
In version mikrotik 2.9.xx I have no problem sending email but in beta 3RC1 I have sometimes during the day problems to send email. I tried to change my smtp server in my email client when I was unable to send mail via smtp.tynec.net. I changed into smtp.my_isp_smtp_server.cz and emails imeadittely gone. I changed my smtp back into smtp.tynec.net and I was unable to send email again.
/ip dns static set [/ip dns static find name="> smtp.tynec.net> "] address=[:resolve "> mail.isp.com> "]
I’m not sure if this helps or not, but you can schedule this script in version 3 to update your static dns entry with the correct ip.
You could also set smtp.tynec.net to the private IP of your router. And setup a dstnat rule like the one below to redirect requests from your customer network to your ISP’s mail server. If you use this, make sure you replace the bold sections with the correct information for your network/setup..
/ip firewall nat add action=dst-nat chain=dstnat comment=“” disabled=no dst-port=25
protocol=tcp src-address=> 192.168.1.0/24 > to-addresses=> 10.1.1.1 > to-ports=25
I hope that helps..
-Gerard
Thanks for help, but I think It was somethink bad in RC1 or it was bad upgrade.
I downgraded to v 2.9.45 and upgraded to V3.0 RC2.
The problem still not appeared 
I hope this solved the problem.
And after this I finally see all of my interfaces.