Can't send article to sql.ru: 411 Failed - Please use Windows-1251 or KOI8-R encoding.

[Oleksandr Gavenko]

I can read articles from sql.ru and post with Latin charset and ever with
Russian *From*.

But when *Body* have Russian letters it returns:

  411 Failed - Please use Windows-1251 or KOI8-R encoding.

I try send:

  Привет!
  </#multipart>

but server policy forbid attachment in mail:

  411 Failed - Please send plain messages. No HTML or attachments is accepted!

So I try:

  (set 'gnus-group-posting-charset-alist '(("^sqlru\\." cp1251 (cp1251))))

But this doesn't help me...

sql.ru have NNTP gateway to discussion Russian forum and require
authentication for reading/posting and have *sql.test* group.

-- 
Best regards!