Thanks for your input but i'm not new in IT business so please ... anyway, back on track ... is not only one DIR-825, i've tested/configured 4 pieces, all have the same problem. All come with 2.05EU but from DEC.2010 and as usual check for firmware update on router doesn't work. Your post made me look for 2.05 from IAN.2012 (thanks for that) and indeed i found DIR-825_fw_revb_205EUb09_07_all_multi_20120106.zip. Flashed on 2 devices but nothing, is not sending anything is not even trying, i've watched the mail server logs in real time, no connection from my IP.
Restore to factory defaults after firmware update doesn't help either.
I've managed to understand, i've used another server and i saw from logs there are some problems in header, most likely thats it, some servers with strict antispam policy reject from the start messages with no FROM / TO headers. So ... is not fine at all.
Content analysis details: (1.5 points, 5.0 required)
pts rule name description
---- ---------------------- --------------------------------------------------
-0.0 T_RP_MATCHES_RCVD Envelope sender domain matches handover relay domain
1.0 MISSING_HEADERS Missing To: header
-1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000]
1.0 MISSING_FROM Missing From: header
1.4 MISSING_DATE Missing Date: header