Strange symbols in email notifications

[Evadik]

When I receive email notification from mantis subject often contains some strange symbols in the subject.
In general all the subject is readable but few letters are strange symbols instead of chars.
I use cyrillic. And it relates to subject only. I read my mail in gmail if it makes any difference.
What can the reason?

[olegos]

In your Gmail, could you do "Show original" (from the message menu, top right), and cut & paste the Subject line here.

[Evadik]

Subject: =?utf-8?B?W1JlYWx0b3ItT25saW5lIDAwMDAwMzddOiDQpNGD0L3QutGG0LjQvtC90LDQ?=
=?utf-8?B?uyAi0L/QvtC00YXQvtC00Y/RidC40LUg0L/RgNC10LTQu9C+0LbQtdC90LjR?=
=?utf-8?B?jyIg0L3QsNGF0L7QtNC40YIg0L3QtSDQstGB0LUg0L/RgNC10LTQu9C+0LbQ?=
=?utf-8?B?tdC90LjRjw==?=

[Evadik]

Here is another one:
Subject: =?utf-8?B?W1JlYWx0b3ItT25saW5lIDAwMDAwMzRdOiDQl9Cw0L/RgNCw0YjQuNCy0LDQ?=
=?utf-8?B?tdC80L7Qs9C+INGE0LDQudC70LAg0L3QtSDRgdGD0YnQtdGB0YLQstGD0LXR?=
=?utf-8?B?giDQuNC70Lgg0L7QvSDQvdC10LTQvtGB0YLRg9C/0LXQvQ==?=

[olegos]

Bug #8572. I've added a note about your case.

[Evadik]

Thank you!