How do I know if an Email had a read receipt and how does this affect my different devices?

Question

I've just had a discussion with a colleague about email read receipts and after a little Google research I haven't found any solid information on them.

As a recipient I open my email in either Mozilla Thunderbird or on my iPhone. My email is setup from a company managed G-mail account.

My question is how do I know that someone has requested a read receipt?

Will Thunderbird and my iPhone both send it back automatically, or will they request my approval?

How can I disable this feature?

Answer 1

Will Thunderbird and my iPhone both send it back automatically, or will they request my approval?

In Thunderbird you can select what action should be taken. The setting for this are under [Tools] [Account settings] "Return receipts"

I have no iPhone, so someone else will have to answer that part.