I am travelling and want to contact a member who has asked for a book. I can mail the book, but the date is not inthe drop down file for the day I can mail. I want to tell member that I can mail a day later. How do I write to that person.

You have to accept the book (choose the latest date available) and then there will be a PM button next to the book on the transaction page.

Just remember that even if they agree to a later date, it you don't mark it mailed by the deadline the system will cancel it and reorder it for her, from someone else.

But there is a two-day grace period to mark the book mailed from the date you choose.  So if you choose to mail on Friday, you have until Sunday to mark the book mailed.  You can also mark the book mailed early provided you do mail the book within 48 hours.