Hi,
for some time i see in mailing list properties page the following..
seems like a broken html tag. my version is updated.. Is there a problem
with DA or maybe a broken theme?
Something's broken. Do you see it in new mailing lists as well?
I'd contact your support group; if you bought your license from DirectAdmin, then perhaps they'll help if you have a full license with support. Otherwise if your license comes from a datacenter you should ask them for support.
If you own a license and support has expired you may want to hire someone who can trace that all for you.
Or just try reinstalling your theme, to see if that solves it .