debian 里面的 exim4 出现 Message is frozen

[nbweb]

美帝的 vps，debian 10,安装了 exim4，发不了邮件，查看日志发现：Message is frozen

2021-08-10 19:35:16 Start queue run: pid=2017
2021-08-10 19:35:16 1mCldf-0007O2-AJ Message is frozen
2021-08-10 19:35:16 1mD87D-0008Ue-46 Message is frozen
2021-08-10 19:35:16 End queue run: pid=2017
2021-08-10 20:05:16 Start queue run: pid=2077
2021-08-10 20:05:16 1mCldf-0007O2-AJ Message is frozen
2021-08-10 20:05:16 1mD87D-0008Ue-46 Message is frozen
2021-08-10 20:05:16 End queue run: pid=2077
2021-08-10 20:35:16 Start queue run: pid=2141
2021-08-10 20:35:16 1mCldf-0007O2-AJ Message is frozen
2021-08-10 20:35:16 1mD87D-0008Ue-46 Message is frozen
2021-08-10 20:35:16 End queue run: pid=2141
2021-08-10 21:05:16 Start queue run: pid=2210
2021-08-10 21:05:16 1mCldf-0007O2-AJ Message is frozen
2021-08-10 21:05:16 1mD87D-0008Ue-46 Message is frozen

这个是什么情况？