| lwIP
    2.1.2
    Lightweight IP stack | 
| Data Fields | |
| enum smtp_session_state | state | 
| u16_t | timer | 
| char | tx_buf [255+1] | 
| const char * | from | 
| u16_t | from_len | 
| const char * | to | 
| u16_t | to_len | 
| const char * | subject | 
| u16_t | subject_len | 
| const char * | body | 
| u16_t | body_len | 
| u16_t | body_sent | 
| smtp_result_fn | callback_fn | 
| void * | callback_arg | 
| char * | username | 
| char * | pass | 
| char | auth_plain [32+32+3] | 
| size_t | auth_plain_len | 
struct keeping the body and state of an smtp session
| char smtp_session::auth_plain[32+ 32+3] | 
Username and password combined as necessary for PLAIN authentication
| size_t smtp_session::auth_plain_len | 
Length of smtp_auth_plain string (cannot use strlen since it includes \0)
| const char* smtp_session::body | 
this is the body of the mail to be sent
| u16_t smtp_session::body_len | 
this is the length of the body to be sent
| u16_t smtp_session::body_sent | 
amount of data from body already sent
| void* smtp_session::callback_arg | 
argument for callback function
| smtp_result_fn smtp_session::callback_fn | 
callback function to call when closed
| const char* smtp_session::from | 
source email address
| u16_t smtp_session::from_len | 
size of the sourceemail address
| char* smtp_session::pass | 
Password to use for this request
| enum smtp_session_state smtp_session::state | 
keeping the state of the smtp session
| const char* smtp_session::subject | 
subject of the email
| u16_t smtp_session::subject_len | 
length of the subject string
| u16_t smtp_session::timer | 
timeout handling, if this reaches 0, the connection is closed
| const char* smtp_session::to | 
target email address
| u16_t smtp_session::to_len | 
size of the target email address
| char smtp_session::tx_buf[255+1] | 
helper buffer for transmit, not used for sending body
| char* smtp_session::username | 
Username to use for this request