Issue:
Missing newline between header and attachment
Issue seen with email clients viz., AppleMail and YahooMail. Attachment is not renderable.
Some clients like Google mail, Samsung mail tolerate the issue.
Fix:
Added newline between header and attachment.
Closes https://github.com/espressif/esp-idf/issues/6098
Signed-off-by: Vikram Dattu <vikram.dattu@espressif.com>
This is based on `ssl_mail_client` from mbedtls.
The client also adds functionality to send attachments.
Signed-off-by: Vikram Dattu <vikram.dattu@espressif.com>