For cyrillic message body I "resolved" the issue by using latin characters instead of russian ones.

Some receiver e-mail addresses contain unicode characters like

test@tööd.com

Trying to use CDO2000 to send to those addresses throws error

ERROR: :1429 # send # 213 # 0x0000020F The server rejected one or more recipient addresses. The server response was: 501 5.1.3 Bad recipient address syntax

I tried

EXTERNAL PROCEDURE cdo2000.prg
loMail = NEWOBJECT("Cdo2000", "Cdo2000.fxp")
WITH loMail
	SYS(3101 ,65001)
	.cTo = strconv(cRecipients,9,  1257, 1 )
...

But bad recipient address error still occurss. I also tried

.cCharset = 'UTF-8'

and in cdo2000.prg added comprop

WITH This
.ClearErrors()
.oCfg = CREATEOBJECT("CDO.Configuration")
// Added
COMPROP(.oCfg, "UTF8",1)
.oMsg = CREATEOBJECT("CDO.Message")
// Added
COMPROP(.oMsg, "UTF8",1)
.oMsg.Configuration = This.oCfg
ENDWITH

but problem persists.
I also tried blat.dll to send email this this also throws error.

How to send e-mail to address test@tööd.com from FoxPro ?

Mozilla Thunderbird send e-mail to this address without issues.