Text file conversation from ISO-8859-2 to UTF-8

[ssimop]

I would like to convert into UTF-8 the following line in a .txt (.eml) file.

Subject: =?ISO-8859-7?B?RmF4IOrh6SBBY3JvYmF0IFdyaXRlcnMgzO/t3OT57SDRwcU=?=



Code page identifier is 28597.

I would appreciate any advice.

Thanks in advance.