I have a problem with the message subject: when I insert one of the preferred fields into the message subject, the whole subject become unreadable like =?utf-8?B?U1VCTUlUVEVEOiBub3RpZmljYXR. Best of my guess is that cyrillic character is present in the field, but I can't determinate which one and where is it.
Who can advise any recipe how to find such character and how to prevent appearing such problem in future? Is it possible to make a special filter?
Any help is appreciated.