When sending my self a email from my Iphone my deflut adds to it befor sending.

When sending my self a email from my Iphone to my yahoo email account it adds random letters or numbers and a the @ sign to the end of my email address and is undeliverables. Then I can go look at my email contacts in yahoo and the changed email is in there. If I delete them all I can then send the email. Then next time i send myself a email it starts all over. The default account used to send and receive email is the same yahoo account on my iphone .

Also It will not let me change the email address before I send it and then stores that email address