I noticed that Universal Search doesn't search all emails. Is there a limitation as to how many emails it can search? For example, I have a client named "Kay" and have three emails with her name in the email's message body. Universal Search only pulls up two of the three emails... but omits the last one. Oddly enough, after deleting the two emails with "Kay" in the message, Universal Search would not find the last one. I made sure that both my email accounts (I have two on my phone) were checked off in the Universal Search options.
The way I search for just emails is by going into my messages folder and Clicking S for search.
Then typing query.
That's really strange... because even if I search using the method you stated, the email is not found. It's in there and "Kay" in the the message body. I also tried searching other words in that email and they are not appearing in search either.
