Arduino NANO 33 IOT: Sending 2 mails OK, following FAILS

Hi Renzo,

I use Arduino NANO 33 IOT, latest WiFiNINA version 1.8.13,
latest EMailSender version 2.4.2 libraries. Arduino NANO has
uploaded certificate for gmail.com:443 domain.

I came across the same faulty behaviour of the EMailSender library like
Paul Bozoian reported on 30 September 2021 at 16:55″:
> I use a MKR1010 WiFi, code will send email correctly two times but on the
> third and subsequent attempts will not connect to mail server. Any ideas?

First two emails are sent without a problem, 3+ in a row
fails with an error (output with EMAIL_SENDER_DEBUG enabled):

ONLY ONE RECIPIENTmultiple destination and attachments
Insecure client:0
smtp.gmail.com
465
### client.connect(this->smtp_server, this->smtp_port) Failed!
Status: 0
Code: 2
Desc: Could not connect to mail server



//source file: EmailSender.cpp around line 400
DEBUG_PRINTLN(this->smtp_server);
DEBUG_PRINTLN(this->smtp_port);
if(!client.connect(this->smtp_server, this->smtp_port)) {
response.desc = F("Could not connect to mail server");
response.code = F("2");
response.status = false;
return response;
}

Some additional info:
* WIFI connectivity is ON before and after email sending attempts, I ping  8.8.8.8 from NANO right after sending attempts without a problem.
* Gmail does not block my sending attempts, I checked it via another python script.
* BUT! When I call WiFi.disconnect(); WiFi.end(); after each attempt & before a new one WiFi.begin(), email sending works without any problem.

This is just a quick workaround, not a solution.
Please, could you take a look at it?

Thanks for your time!
Irgo