Does not send Mail php mail(): server reason?

Question

Mail server

In general, it worked earlier after a while and the installation of updates was somehow not particularly noticed, everything works and quickly from the sendmail, but the question was raised that the scripts stopped sending mail exactly php mail ()
which could be the reason, that's the joke, that for the test, they took the same keo hosting, and everything works there. letters come to Yandex even with the substitution of the addressee's mail.
And for the life of me on the server, mail was created for the test and it was named in the sender, it still didn’t reach Yandex, below I’ll give the log
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Apr 25 04:57:17 srv1 sendmail[23243]: v3P1vHtX023243: Authentication-Warning: srv1.fsb26 .ru: borz set sender to [email protected] using -f
Apr 25 04:57:18 srv1 sendmail[23243]: v3P1vHtX023243: [email protected], size=113, class=0, nrcpts=1, msgid=<[email protected]> , [email protected]
Apr 25 04:57:18 srv1 sm-mta[23244]: STARTTLS=server, relay=localhost [127.0.0.1], version=TLSv1/SSLv3, verify=NO, cipher=DHE-RSA- AES256-GCM-SHA384, bits=256/256
Apr 25 04:57:18 srv1 sendmail[23243]: STARTTLS=client, relay=[127.0.0.1], version=TLSv1/SSLv3, verify=FAIL, cipher=DHE- RSA-AES256-GCM-SHA384, bits=256/256
Apr 25 04:57:18 srv1 sm-mta[23244]: v3P1vIrw023244: from=, size=425, class=0, nrcpts=1, msgid=<201704250157. [email protected]>, proto=ESMTP, daemon=MTA-v4, relay=localhost [127.0.0.1]
Apr 25 04:57:18 srv1 sendmail[23243]: v3P1vHtX023243: [email protected], [email protected] (549/535), delay=00:00:01, xdelay=00: 00:00, mailer=relay, pri=30113, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (v3P1vIrw023244 Message accepted for delivery)
Apr 25 04:57:18 srv1 sm -mta[23246]: v3P1vIrw023244: to=\\virtuser_561, delay=00:00:00, xdelay=00:00:00, mailer=local, pri=60693, dsn=2.0.0, stat=Sent
Apr 25 04 :57:18 srv1 sm-mta[23246]: STARTTLS=client, relay=mx.yandex.ru., version=TLSv1/SSLv3, verify=FAIL, cipher=ECDHE-RSA-AES128-GCM-SHA256, bits=128 /128
Apr 25 04:57:19 srv1 sm-mta[23246]: v3P1vIrw023244: [email protected], delay=00:00:01, xdelay=00:00:01, mailer=esmtp, pri=60693, relay =mx.yandex.ru. [87.250.250.89], dsn=2.0.0, stat=Sent (Ok: queued on mxfront2h.mail.yandex.net as 1493085439-3p47VQpeEO-vIM49irw)
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Or is assassin spam to blame?

Answer 1

relay=mx.yandex.ru. [87.250.250.89], dsn=2.0.0, stat=Sent (Ok: queued on mxfront2h.mail.yandex.net as 1493085439-3p47VQpeEO-vIM49irw)
How did it not get there if Yandex reported?