Manson don't want "a pen pal" he has always had thousands of them since 1969. I did wonder very slightly about the "t + o =" because he has used these before yet with a quick comparison the writing still looks not quite right. As far as the upside down "Mano" I will consed, that maybe, just maybe . . . that writing is authentic. So, this letter was sent to you, Kellyo123? Did you receive any others?
The t plus o is in Manson's handwriting. The addressed part in the front is his Xman. I know this because his Xman sent me a separate letter as he thought I was a Irish woman and he wanted a pen pal. The Mano in the lower left upside down is also Manson.
This is not Manson's hand writing. This letter is more then likely from one of what he calls his, "x-men" or other inmates in the same prison with him who reply to some of his mail for him. Sorry, its easy to do the comparison because Charles Manson's writing is very distinct.
If you look on the left bottom of the first photo, you will see where Manson put his name with 6 dots around it. The back Is also in Manson handwriting. You can compare the writing on Google.