Assuming you're displaying the "Send" box when submit is clicked. Why not collect the values in the form, validate them with logical statements and if they all return true then the data must be valid and you can display the image.
I'm a little confused about your question so sorry if this is inaccurate.
some of free email hosting companies are having a these type of quality to see the quick message and if you can optimize according to you by taking mail hosting services...
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