Hikvision DS-7616NXI-I2 / 16P/4S alert email attached images are low quality?

[apez84]

Dears,

I've set the email on motion alert on my DS-7616NXI-I2 / 16P/4S NVR.

The attached images arrive with very poor quality (image files of say only 14kB size).

I can't find where I can modify that value to obtain a better quality of attached images?

Cameras attached are DS-2CD2345FWD-I .

Many thanks to whom can help with this,

Regards,

Francesco