Arduino memory availability monitoring and email sending

Hello! As part of the realization of my debug monitoring function on my connected beehive project with sending emails via an Ethernet shield and Arduino Mega I noticed this: 14: 10: 38.500 -> Correct assembly and card present 14: 10: 40.937 -> Number of tests requested: 2 14: 10: 40.937 -> <span style="text-decoration: underline;">2784</span> = free memory before email 14: 10: 40.971 -> Hi, it's Hive N ° 2 to give you my IP address. ..... then once the sending of this first email is done: 14: 10: 42.124 -><span style="text-decoration: underline;"> 2155</span> = memory after sending the 1st email 14: 10: 42.090 -> resp code = 0 14: 10: 42.124 -> Message sent! then just after sending a second email: 14: 10: 42.328 -> <span style="text-decoration: underline;">2053</span> = free memory before sending second email 14: 10: 42.367 -> Hi, it's Hive # 2, I just adjusted the time on the clock 14: 10: 43.556 -> resp code = 0 14: 10: 43.590 -> <span style="text-decoration: underline;">1940</span> = memory after sending the second email 14: 10: 43.590 -> Message sent! 14: 10: 43.590 -> we just readjusted the clock! 14: 10: 43.624 -> Free memory: <span style="text-decoration: underline;">2242</span> And after the free memory of the Arduino remains at 2242, however before sending the 2 emails it was 2784. A loss of 542 bytes ... Has anyone tracked this problem and found the origin of it? Thank you PS to know the available memory I use the function: freeMemory ();