I just installed the 6540 patch and am still having the same issue with a handful of users. Most of the issues were fixed but those that didn't seem to have the issue are now having the issue. Very strange.
SMTP Logs after upgrade to 6540
[2017.11.29] 15:16:17 [71.201.147.140][32767822] rsp: 220 mail.centricweb.net Wed, 29 Nov 2017 21:16:17 +0000
[2017.11.29] 15:16:17 [71.201.147.140][32767822] connected at 11/29/2017 3:16:17 PM
[2017.11.29] 15:16:17 [71.201.147.140][32767822] cmd: EHLO PC
[2017.11.29] 15:16:17 [71.201.147.140][32767822] rsp: 250-mail.centricweb.net Hello [71.201.147.140]250-SIZE 104857600250-AUTH LOGIN CRAM-MD5250-STARTTLS250-8BITMIME250 OK
[2017.11.29] 15:16:17 [71.201.147.140][32767822] cmd: AUTH LOGIN
[2017.11.29] 15:16:17 [71.201.147.140][32767822] rsp: 334 VXNlcm5hbWU6
[2017.11.29] 15:16:17 [71.201.147.140][32767822] Authenticating as User@domain.com
[2017.11.29] 15:16:17 [71.201.147.140][32767822] rsp: 334 UGFzc3dvcmQ6
[2017.11.29] 15:16:17 [71.201.147.140][32767822] rsp: 235 Authentication successful
[2017.11.29] 15:16:17 [71.201.147.140][32767822] Authenticated as User@domain.com
[2017.11.29] 15:16:17 [71.201.147.140][32767822] cmd: MAIL FROM: <User@domain.com>
[2017.11.29] 15:16:17 [71.201.147.140][32767822] rsp: 250 OK <User@domain.com> Sender ok
[2017.11.29] 15:16:17 [71.201.147.140][32767822] cmd: RCPT TO: <d.dax@domain.com>
[2017.11.29] 15:16:17 [71.201.147.140][32767822] rsp: 250 OK <d.dax@domain.com> Recipient ok
[2017.11.29] 15:16:17 [71.201.147.140][32767822] cmd: DATA
[2017.11.29] 15:16:17 [71.201.147.140][32767822] rsp: 354 Start mail input; end with <CRLF>.<CRLF>
[2017.11.29] 15:16:17 [71.201.147.140][32767822] rsp: 550 From address must match authenticated address
[2017.11.29] 15:16:17 [71.201.147.140][32767822] rsp: 550 From address must match authenticated address
[2017.11.29] 15:16:17 [71.201.147.140][32767822] rsp: 550 From address must match authenticated address
[2017.11.29] 15:16:17 [71.201.147.140][32767822] rsp: 550 From address must match authenticated address
[2017.11.29] 15:16:17 [71.201.147.140][32767822] rsp: 250 OK
[2017.11.29] 15:16:17 [71.201.147.140][32767822] Successfully wrote to the HDR file. (c:\SmarterMail\Spool2\SubSpool18\402826477.hdr)
[2017.11.29] 15:16:17 [71.201.147.140][32767822] Data transfer succeeded, writing mail to 402826477.eml
[2017.11.29] 15:16:19 [71.201.147.140][32767822] cmd: QUIT
[2017.11.29] 15:16:19 [71.201.147.140][32767822] rsp: 221 Service closing transmission channel
[2017.11.29] 15:16:19 [71.201.147.140][32767822] disconnected at 11/29/2017 3:16:19 PM
Delivery Logs says the message was delivered and the end client did get the email just we keep getting bounce backs says 550 error.
Barbara Renowden President / Co-Founder Centric Web, Inc. https://www.centricweb.com