Bought three two-pack batteries, tested four of the them. At full charge all four are below 2800mah.
UPDATE:
I was reading the mAh display incorrectly. It tells you how many mAh hours went into the battery during the charging period not the battery capacity. Will be draining batteries and trying it again. My bad.
Update #2:
Only had time to drain and charge one 18650 so far (running 0.5A takes a while), it took 3519 mAh. Going to check a few others as well but happy so far.
Hey There!
What was your testing method for our T35U 18650 Batteries? Most consumer chargers cannot set the discharge voltage that would be required to properly give an accurate reading. If you’d like to contact us to discuss the issue, please reach out to Support_Team@Tenergy.com
I figured out last night while charging some Tenergy AAA, C and D cells that I was reading the display incorrectly. The display tells you how many mAh’s went into the battery during the charging period (like a gas pump). I’m draining one of the 18650’s now and going to try it again and see what the results are.
User error 
FYI - I am using the XTAR VC4 (running 0.5 amps) for charging.
Hey,
No worries. Glad to hear that you got batteries that live up to your expectations, let us know if you have any questions : )
@TenergyOfficial
What is the recommended cutoff voltage for these cells? The advertised capacity is tremendous!
From the vendor:
The cutoff voltage is 2.5V