when Asynchronous Processing is not used,i found an intersting thing.After 354 Start mail input; end with <CRLF>.<CRLF>

If sender server send: SENT: [nl].

It is 100% no problem

If sender server send: SENT: <\r\n.\r\n>

Most of the case,it has problem,the details looks like below:

(1)

2021-05-22 22:54:00,140 - [     5437] S <-- 354 Start mail input; end with <CRLF>.<CRLF>
2021-05-22 22:55:10,965 - [     5437] S <-- 250 2.6.0 Queued mail for delivery
2021-05-22 22:55:11,137 - [     5437] C --> QUIT
2021-05-22 22:55:11,137 - [     5437] S <-- 221 Good bye. Hope to see you again

(2)

2021-05-22 22:56:15,831 - [     5438] S <-- 354 Start mail input; end with <CRLF>.<CRLF>
2021-05-22 22:57:21,496 - [     5438] S <-- 250 2.6.0 Queued mail for delivery
2021-05-22 22:57:21,496 - [     5438] ~~~~~~~~~~~~ Connection Terminated (66372:515) Unexpected input termination. Connection terminated without a graceful QUIT

Is it a bug? Seems Xeams not understanding \r\n ???