In letters sent zabbix v3.0.1 and v3.0.2 is not working encoding utf8,
Only signs (????) not Cyrillic,
Example of receiving a letter from zabbix:
message header
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Subject: PROBLEM: speed MS TCP Loopback interface. ????????
MIME-Version: 1.0
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: base64
Trigger: speed MS TCP Loopback interface.
text: ????????
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