Glad the mail server config document was helpful.
When you did the version upgrade, did you, by chance, also change to a different server? If so, did you change IP addresses?
Do you have any users who are using one e-mail account to receive and another to send? IE: Is anyone using a an AOL [or other account] to send and using the account on your server to receive?
When you did the upgrade, was it a major or minor version upgrade? From what version to what version? [Some major version upgrades may require additional setting changes in SmarterMail.]
If it was a major version upgrade, did you uninstall the prior version and then install the newest version?
If it was a minor version upgrade, did you stop both the SmarterMail service and the IIS service, do the upgrade and then restart the service?
Have you tried rebooting the server on which SmarterMail is installed?
If none of those items are the issue, you may have to open a ticket with SmarterTools or engage the services of a third-party to help you resolve this.
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