Mail conversation was terminated after 250 Queued mail for delivery，and the sending mail server keeps sending the same email.

2021-03-13 10:35:13,937 ERROR Zipper - Unable to view zipped bytes. Unexpected record signature: 0XE011CFD0
2021-03-13 10:35:13,979 ERROR Zipper - Unable to view zipped bytes. Unexpected record signature: 0XE011CFD0
2021-03-13 10:35:13,963 ERROR Zipper - Unable to view zipped bytes. Unexpected record signature: 0XE011CFD0
2021-03-13 10:35:13,994 ERROR Zipper - Unable to view zipped bytes. Unexpected record signature: 0XE011CFD0
2021-03-13 10:35:14,014 ERROR Zipper - Unable to view zipped bytes. Unexpected record signature: 0XE011CFD0
2021-03-13 10:35:14,016 ERROR Zipper - Unable to view zipped bytes. Unexpected record signature: 0XE011CFD0

2021-03-13 10:35:09,520 - [ 4046] ************ New connection from: 202.108.3.167:25
2021-03-13 10:35:09,714 - [ 4046] C --> HELO mail3-167.sinamail.sina.com.cn
2021-03-13 10:35:09,714 - [ 4046] S <-- 250 202.108.3.167. Pleased to meet you
2021-03-13 10:35:09,905 - [ 4046] C --> MAIL FROM:<longshiXXXXXX@sina.com>
2021-03-13 10:35:09,906 - [ 4046] S <-- 250 OK
2021-03-13 10:35:10,099 - [ 4046] C --> RCPT TO:<jeffrey_shen@mydomain.com>
2021-03-13 10:35:10,100 - [ 4046] S <-- 250 OK
2021-03-13 10:35:10,298 - [ 4046] C --> DATA
2021-03-13 10:35:10,298 - [ 4046] S <-- 354 Start mail input; end with <CRLF>.<CRLF>
2021-03-13 10:35:15,896 - [ 4046] S <-- 250 2.6.0 Queued mail for delivery
2021-03-13 10:35:16,097 - [ 4046] ~~~~~~~~~~~~ Connection Terminated (6577:45) Unexpected input termination. Connection terminated without a graceful QUIT.

2021-03-13 10:35:09,523 - [ 4047] ************ New connection from: 202.108.3.165:25
2021-03-13 10:35:09,707 - [ 4047] C --> HELO mail3-165.sinamail.sina.com.cn
2021-03-13 10:35:09,708 - [ 4047] S <-- 250 202.108.3.165. Pleased to meet you
2021-03-13 10:35:09,891 - [ 4047] C --> MAIL FROM:<longshiXXXXXX@sina.com>
2021-03-13 10:35:09,891 - [ 4047] S <-- 250 OK
2021-03-13 10:35:10,074 - [ 4047] C --> RCPT TO:<tingting_wang@mydomain.com>
2021-03-13 10:35:10,075 - [ 4047] S <-- 250 OK
2021-03-13 10:35:10,264 - [ 4047] C --> DATA
2021-03-13 10:35:10,264 - [ 4047] S <-- 354 Start mail input; end with <CRLF>.<CRLF>
2021-03-13 10:35:14,860 - [ 4047] S <-- 250 2.6.0 Queued mail for delivery
2021-03-13 10:35:15,053 - [ 4047] ~~~~~~~~~~~~ Connection Terminated (5530:45) Unexpected input termination. Connection terminated without a graceful QUIT.

2021-03-13 10:35:10,341 - [ 4048] ************ New connection from: 202.108.3.165:25
2021-03-13 10:35:10,527 - [ 4048] C --> HELO mail3-165.sinamail.sina.com.cn
2021-03-13 10:35:10,527 - [ 4048] S <-- 250 202.108.3.165. Pleased to meet you
2021-03-13 10:35:10,713 - [ 4048] C --> MAIL FROM:<longshiXXXXXX@sina.com>
2021-03-13 10:35:10,713 - [ 4048] S <-- 250 OK
2021-03-13 10:35:10,900 - [ 4048] C --> RCPT TO:<beibei_liu@mydomain.com>
2021-03-13 10:35:10,901 - [ 4048] S <-- 250 OK
2021-03-13 10:35:11,089 - [ 4048] C --> DATA
2021-03-13 10:35:11,089 - [ 4048] S <-- 354 Start mail input; end with <CRLF>.<CRLF>
2021-03-13 10:35:14,884 - [ 4048] S <-- 250 2.6.0 Queued mail for delivery
2021-03-13 10:35:15,078 - [ 4048] ~~~~~~~~~~~~ Connection Terminated (4737:45) Unexpected input termination. Connection terminated without a graceful QUIT.

I try to gooogle this error,i found as below:

.xlsx  HSSFWorkbook
.xls  XSSFWorkbook

Seems such error happen when the attached file is office2003 format  .doc  .xls

The error you see in the logs related to ZIP files is not related to the repeated emails. I say that because filtering in Xeams occurs in a different thread. The primary thread, which accepts the email is only responsible for downloading the message.

This is the reason why the time between the start of the email and the end is less than 3 seconds. See below.

2021-03-13 10:35:11,089 - [ 4048] S <-- 354 Start mail input; end with <CRLF>.<CRLF>
2021-03-13 10:35:14,884 - [ 4048] S <-- 250 2.6.0 Queued mail for delivery

For some reason, the sender is terminating the connection before sending a QUIT command. You will have to contact the sender and see their logs to determine why does it keep sending the message over and over again.

Now, let me talk about XLS files. Xeams tries to look inside Excel sheets to see if they have harmful contents. Files with an extension *.XLSX are actually zipped. Often folks rename *.XLS files to *.XLSX to avoid detection. You would see an error logged when this happens. Rest assured, this error has nothing to do with the repeated emails you're getting.

Noted with tks,maybe it is the network issue.