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The warning comes in the form of the "Deposit Limit" above the input estimate edit box. This value shows the remaining amount you can transact with us for the day at your current allowed daily transaction volume.

If you put in an estimated amount above this value, the deposit limit will turn red to indicate the amount you're planning to send would exceed your daily limit. For example, in the screenshot below the user is asking for an estimate for 7 ETH which exceeds his remaining daily limit of 6.887 ETH).

Also, it's best to avoid pushing too close to your limit as the USD value of the input can fluctuate.

Ah ok. It does not block if the amount is to high. The user can send the money even it is to high. If this happens, it is pending and an admin must look at it.

Isn't it possible to disable the send button if the amount is to high?

The sending isn't done from our site, so we can't block it. In general, there's no way to block someone from sending cryptocurrency to you.

Ok, thanks for your efforts!