Direct Reply from GMail User's Response

Server Version 0.70.4
LDAP Enabled
IMAP Server: imap.gmail.com
Port: 993
Username: XXXX@gmail.com

Response after user responded via email (gmail)

"I20181018-22:20:35.258(0) => 'A6 UID SEARCH UNSEEN'
I20181018-22:20:35.330(0) <= '* SEARCH 35'
I20181018-22:20:35.332(0) <= 'A6 OK SEARCH completed (Success)'
I20181018-22:20:35.334(0) => 'A7 UID FETCH 35 (X-GM-THRID X-GM-MSGID X-GM-LABELS MODSEQ UID FLAGS INTERNALDATE BODYSTRUCTURE BODY[HEADER.FIELDS (FROM TO DATE MESSAGE-ID)] BODY[1])'
I20181018-22:20:35.547(0) <= '* 2 FETCH (X-GM-THRID 1614703432240661464 X-GM-MSGID 1614703473666760168 X-GM-LABELS ("\\Important") UID 35 MODSEQ (9826) INTERNALDATE "18-Oct-2018 22:20:31 +0000" FLAGS (\Seen) BODY[HEADER.FIELDS (FROM TO DATE MESSAGE-ID)] {214}'
I20181018-22:20:35.551(0) <= '* 2 FETCH (X-GM-THRID 1614703432240661464 X-GM-MSGID 1614703473666760168 X-GM-LABELS ("\\Important") UID 35 MODSEQ (9826) INTERNALDATE "18-Oct-2018 22:20:31 +0000" FLAGS (\Seen) BODY[1] {790}'
I20181018-22:20:35.554(0) <= '* 2 FETCH (X-GM-THRID 1614703432240661464 X-GM-MSGID 1614703473666760168 X-GM-LABELS ("\\Important") UID 35 MODSEQ (9826) INTERNALDATE "18-Oct-2018 22:20:31 +0000" FLAGS (\Seen) BODYSTRUCTURE (("TEXT" "PLAIN" ("CHARSET" "UTF-8") NIL NIL "QUOTED-PRINTABLE" 790 16 NIL NIL NIL)("TEXT" "HTML" ("CHARSET" "UTF-8") NIL NIL "QUOTED-PRINTABLE" 4542 91 NIL NIL NIL) "ALTERNATIVE" ("BOUNDARY" "000000000000d6149a05788831cc") NIL NIL))'
I20181018-22:20:35.564(0) Invalid Email....If not. Please report it.
I20181018-22:20:35.768(0) <= '* 2 FETCH (UID 35 MODSEQ (9833) FLAGS (\Seen))'
I20181018-22:20:35.769(0) <= 'A7 OK Success'
I20181018-22:20:35.771(0) => 'A8 STORE 2 +FLAGS.SILENT (\Deleted)'
I20181018-22:20:36.168(0) <= 'A8 OK Success'
"

Rocket.Chat doesn't see the respond. I wonder if fixing this "I20181018-22:20:35.564(0) Invalid Email....If not. Please report it. " error will remedy this problem, but I do not know how to troubleshoot this problem.

Start with the logged IMAP FETCH exchange and the "Invalid Email....If not. Please report it." message, then trace the email ingestion entry point that processes Gmail replies. Done means Rocket.Chat recognizes the user's direct Gmail response instead of deleting it as invalid.