Last week I began corresponding with a Japanese penpal. I initially addressed her with 丁寧語, but she responded using 尊敬語/謙譲語 so I began responding that way as well. We've been addressing each other with さん付け. In her most recent e-mail she wrote the following (I've replaced the names with aliases):
I assume this is an invitation to call her 亜沙美さん or 京子さん. Since we've only known each other for about a week and are using 敬語 at her instigation, I would not expect to be invited to 呼び捨て. However, her use of quotation marks makes me a little uncertain. Googling suggests that in the common phrase "○○と呼んでください," ○○ is often written without quotation marks, and may or may not be followed by an honorific. Even if it is written without an honorific, based on the context of the examples I found, that does not necessarily seem to constitute an invitation to 呼び捨て. However, if quotation marks are used, and without an honorific, does that constitute an invitation to refer to the person in question as literally indicated, i.e., with no honorific?