How to handle this email error when using custom SMTP settings in Sage 50 Payroll and Sage 50 Accounts.
If you use custom SMTP settings to email documents from Sage 50 Payroll or Sage 50 Accounts, the following error sometimes occurs:
'Error with the address [email address]: Unknown Error. Please check Windows Event Log for more details'.
This issue occurs when using SMTP as the mail provider. The causes are antivirus software and the version of Sage report designer.
The 'Email Protection/Mail Shield' feature in some antivirus software causes this issue.
Open the Windows Event Viewer to view the full error details. ▼ View the full Windows Event Viewer error that this issue causes.
MailKit.Security.SslHandshakeException: An error occurred while attempting to establish an SSL or TLS connection. The server's SSL certificate could not be validated for the following reasons: • The server certificate has the following errors: • The revocation function was unable to check revocation for the certificate. ---> System.Security.Authentication.AuthenticationException: The remote certificate is invalid according to the validation procedure. at System.Net.Security.SslState.InternalEndProcessAuthentication(LazyAsyncResult lazyResult) at System.Net.Security.SslState.EndProcessAuthentication(IAsyncResult result) at System.Threading.Tasks.TaskFactory`1.FromAsyncCoreLogic(IAsyncResult iar, Func`2 endFunction, Action`1 endAction, Task`1 promise, Boolean requiresSynchronization) --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at MailKit.Net.Smtp.SmtpClient.<SslHandshakeAsync>d__8.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at MailKit.Net.Smtp.SmtpClient.<PostConnectAsync>d__9.MoveNext() --- End of inner exception stack trace --- at MailKit.Net.Smtp.SmtpClient.<PostConnectAsync>d__9.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at MailKit.Net.Smtp.SmtpClient.<ConnectAsync>d__10.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at Sage.Email.SMTP.SmtpMailer.<SendMail>d__13.MoveNext()
Software update - 50 Payroll only
If you're using Sage 50 Payroll, download and install the latest version of Sage 50 Payroll.
Check if this resolves the issue. If not, or if the issue occurred for you in Sage 50 Accounts, continue to the antivirus section below.
Antivirus
The next step is to check, and where required, amend antivirus software settings. To keep your system secure, contact your IT support before changing settings in your antivirus software.
With your IT support's approval, locate and disable the 'Scan Outbound emails (SMTP)' setting in your antivirus software.
NOTE:
Sage technical support can't help with amending antivirus software settings.
Issue persists
If the issue still occurs after these steps, contact Sage technical support.
- Solution ID
- 251002161134647
- Last Modified Date
- Thu Jun 25 12:32:19 UTC 2026
- Views
- 0