Replying to a message from: Anonymous

After many try,seems it is the network issue? The sender side email log is as below:

[2021-05-22 22:56:22] RECV (SM21052200001477=>admin@mydomain.com): 354 Start mail input; end with <CRLF>.<CRLF>
[2021-05-22 22:56:22] SEND (SM21052200001477=>admin@mydomain.com): <GO...2151974 bytes>
[2021-05-22 22:56:22] SEND (SM21052200001477=>admin@mydomain.com): <\r\n.\r\n>
[2021-05-22 22:57:24] RECV (SM21052200001477=>admin@mydomain.com): network recv failed at [.]
[2021-05-22 22:57:24] SEND (SM21052200001477=>admin@mydomain.com): <FAIL>
[2021-05-22 22:57:24] SEND (SM21052200001477=>admin@mydomain.com): [0] FAILED: network recv failed at [.]
[2021-05-22 22:57:24] SEND (SM21052200001477=>admin@mydomain.com): Sent FAILED to admin@mydomain.com: network recv failed at [.]

[2021-05-22 22:59:27] RECV (SM21052200001477=>admin@mydomain.com): 354 Start mail input; end with <CRLF>.<CRLF>
[2021-05-22 22:59:27] SEND (SM21052200001477=>admin@mydomain.com): <GO...2151974 bytes>
[2021-05-22 22:59:27] SEND (SM21052200001477=>admin@mydomain.com): <\r\n.\r\n>
[2021-05-22 23:00:29] RECV (SM21052200001477=>admin@mydomain.com): true [.]
[2021-05-22 23:00:29] SEND (SM21052200001477=>admin@mydomain.com): <FAIL>
[2021-05-22 23:00:29] SEND (SM21052200001477=>admin@mydomain.com): [0] FAILED: network recv failed at [.]
[2021-05-22 23:00:29] SEND (SM21052200001477=>admin@mydomain.com): Sent FAILED to admin@mydomain.com: network recv failed at [.]

[2021-05-22 23:42:22] RECV (SM21052200001481=>admin@mydomain.com): 354 Start mail input; end with <CRLF>.<CRLF>
[2021-05-22 23:42:22] SEND (SM21052200001481=>admin@mydomain.com): <GO...667743 bytes>
[2021-05-22 23:42:39] SEND (SM21052200001481=>admin@mydomain.com): <\r\n.\r\n>
[2021-05-22 23:42:48] RECV (SM21052200001481=>admin@mydomain.com): 250 2.6.0 Queued mail for delivery
[2021-05-22 23:42:48] SEND (SM21052200001481=>admin@mydomain.com): QUIT
[2021-05-22 23:43:50] RECV (SM21052200001481=>admin@mydomain.com): network recv failed at [QUIT]
[2021-05-22 23:43:50] SEND (SM21052200001481=>admin@mydomain.com): Sent OK to admin@mydomain.com