How to reduce time needed to send first mail?

[joba-1]

Hi,

I discovered your useful lib yesterday via randomnerdtutorials.

I now use it for a Pir Monitor and noticed the sending of the first mail after boot is very slow.
Certainly this is due to some initialization stuff. Is it possible to do this separately? Usually I have lots of time before the first mail is sent, so I would like to do it beforehand, without actually sending an email.

Cheers,
Joachim

[mobizt]

Are you new to networking?

It is about the networking (on-line) task, instead of off-line task, and you have to wait.

You have to setup WiFi and wait until it connected.
The system time is required before sending message per RFC 822.
You have to set device system time unless library will set it via sending the request to NTP server which takes time.
To establish the SMTP server connection, it also takes time during negotiation too.

[joba-1]

Thanks for your quick reply!

Are you new to networking?

Not really. I wrote a mail client on a unix box about 35 years ago.
But I obviously have difficulties making myself clear. I'll try again:

I agree with what you say above, but I can (and do) connect to wifi at boot, not at first mail sent.
Also I could set time at boot with ntp. Have done that in many other projects. Would your code detect it already has a valid time and skip that step?

In my code I do a smtp connect/sendMail/closeSession for every mail, because time between sends can be hours. No need to maintain a connection. Sending the second and following mails is fast enough this way.

So what I am asking for is this: when sending the first mail there are necessary steps to do that are not needed for following mails. (How) can I do these steps separately at boot, without actually sending a mail.

[mobizt]

Library checks for valid time from your device i.e. from ESP32/ESP8255 timer before sending message. If it was not valid time based on default timestamp, NTP server time requesting will begin.

You don't have to do anything for preparing if your WiFi network and system time are ok.

As I said the SMTP server negotiation takes time just only during message sending.

[mobizt]

Are you new to networking?

I'm talking in embedded device context.

[mobizt]

You should follow the library provided examples instead as many things are updated since the time that tutorial was written.

[joba-1]

Great, this did it:

ESP-Mail-Client/examples/SMTP/Set_Time/Set_Time.ino

Line 104 in 506e2a3

configTime(0, 0, "pool.ntp.org", "time.nist.gov");

now sending the first mail is just as fast as the following mails.