Problem loop stop after my send email function

Hello, while waiting for a solution to my mail problem with orange, I am working on sending mail with gmail. I’m trying to put your program in a function to integrate it into a connected hive program … When I solicit this function (sending email) at the end of sending the main loop stops … I don't understand why at the end of this function I don't go back to the main program ...   I isolated the function in question and I put it below ...  

#include <EMailSender.h>
#include "HX711.h"
#include "SD.h"
#include "SPI.h"
#include "RTClib.h"

#include "Adafruit_Sensor.h"
#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <Ethernet.h> // Ethernet or ethernet2 library only W5500 …

#define DEFAULT_EMAIL_NETWORK_TYPE_ARDUINO NETWORK_W5100

uint16_t SMTP_PORT = 25;
const char *smtp_server = "smtp.orange.fr";
const char *email_login = "xy@wanadoo.fr";
const char *email_from = "xy@wanadoo.fr";
const char *name_from = "roland";
const char *email_password = "password";

#define SECRET_MAC {0x90, 0xA2, 0xDA, 0x10, 0x40, 0x4F}// mac address Ardiuno mega
#define pinCS_SD 4 // we reserve Pin 4 for the SD reader
#define pinCS_ETH 10

IPAddress ip(192, 168, 1, 143); // The default IP address that the shield will take if the box does not assign an IP

byte mac[] = SECRET_MAC; // The MAC address of the shield

String Typefichier = ".csv"; //type of file that we want on SD attention if modification must be modified  fileDescriptor[0].mime = "text/csv"; in the envoimail function!

String NomFichierMensuel; //storage file name previous month
EthernetClient client;
File file; // Creating the file object named file
Sd2Card card;

int nbessai = 2; // number of attempts to send emails in case of failure …
int a = 0;

/* we configure the sender’s mailbox and the server !*/
EMailSender emailSend(email_login, email_password, email_from, name_from,
		smtp_server, SMTP_PORT);

void setup() {
	Serial.begin(9600); //we initialize the serial monitor at 9600 bauds

	pinMode(53, OUTPUT); //mega card to be able to access SD and Ethernet at the same time must be activated

	/*Test to see if the SD card is working */
	if (!card.init(SPI_HALF_SPEED, pinCS_SD))
		Serial.println(F("problem!"));

	else
		Serial.println(F("Correct assembly and card present"));

	/* THE COMMISSIONING OF ETHERNET IS ATTACKED */
	Ethernet.init(pinCS_ETH); // start the ethernet card on pin 10

	char erreur = 0;

	erreur = Ethernet.begin(mac); // We try to start the Ethernet shield WITHOUT an IP address (therefore given via DHCP from the box)

	if (erreur == 0) {
		Ethernet.begin(mac, ip); // forcing the ip address if not acquired by box
		Serial.println(F("IP fixe"));
	}
// end of if error getting dynamic IP!

	Serial.println(F("Init…"));

	delay(1000); //Give the shield a second to initialize
}

void loop() {
	if (a == 0)
		boolean retourmail = envoimail(3, "", 2); // send email swarming alert with 2 attempts to send email

	if (a == 1)
		boolean retourmail = envoimail(2, NomFichierMensuel, 1); //send mensual mail

}

boolean envoimail(int lequel, String NomFichierMensuel, int nbessai) {

	boolean piecejointe;
	String msgsujet;
	String msgcorps;

	switch (lequel) {
	case 1: { // sending mail theft
		piecejointe = 0;
		msgsujet = F("WARNING THEFT of your beehive in progress!");
		msgcorps =
				F(
						"The weight sensor just dropped to less than 5kg, either the scale has a problem, someone is taking your hive away, or you take a thorough visit and test the function …");
		break;
	}

	case 2: { //monthly email
		piecejointe = 1;
		msgsujet = F("Don’t panic, it’s the monthly statement");
		msgcorps = "Please find attached the monthly statement "
				+ NomFichierMensuel + " of beehive n° 1";
		break;
	}

	case 3: { // sending email swarming…
		piecejointe = 0;
		msgsujet = F("CAUTION possible swarming");
		msgcorps =
				F(
						" The weight sensor has just lost 5 kg quickly, either you intervene on the hive or there is swarming.");
		break;
	}

	} // end of switch

// start of sending email

	EMailSender::EMailMessage message; // structure defined in EmailSender.h

	message.subject = msgsujet;
	message.message = msgcorps;

	EMailSender::FileDescriptior fileDescriptor[piecejointe]; // structure defined in EmailSender.h 2 = 2 attachments

	fileDescriptor[0].filename = NomFichierMensuel;
	fileDescriptor[0].url = NomFichierMensuel;
	fileDescriptor[0].mime = "text/csv";
	fileDescriptor[0].encode64 = false;
	fileDescriptor[0].storageType = EMailSender::EMAIL_STORAGE_TYPE_SD;

	EMailSender::Attachments attachs = { piecejointe, fileDescriptor }; // structure defined in EmailSender.h

	const char *arrayOfEmail[] = { "dupont@gmail.com", "abc@wanadoo.fr" };

	EMailSender::Response resp = emailSend.send(arrayOfEmail, 2, message,
			attachs);

	Serial.print(F("Shipment status : "));

	Serial.println(resp.status);
	Serial.print(F("resp Code: "));
	Serial.println(resp.code);
	Serial.print(F("Description : "));
	Serial.println(resp.desc);

// redo an e-mail return test …

	if (nbessai > 0 && resp.code != 0) {
		EMailSender::Response resp = emailSend.send(arrayOfEmail, 2, message,
				attachs);
		Serial.println(F("we try again…"));

	}

	nbessai = nbessai - 1;

	Serial.println(F("send of mail"));

	return (resp.code);

} //end of function send mail

  If anyone sees how to fix my problem ... Thanks in advance!