Out of 8 reports 4-5 are sending rest are bouncing.
I am using send outlook mail message
This issue because of your mailbox size.
Log into Outlook on the web and clear out old mail - start with deleted items then work on other folders if you can’t get it low enough.
Some people prefer to repeat step 2 to clear the Deleted items folder. If you do this, do step 3 every few thousand messages.
@Manju_Reddy_Kanughula ,
if it is shared to some ids, then probably you should check and confirm that the mail ids provided is correct, no extr added spaces in between
Also are you sharing the mail in a loop or At once for multiple email ids?