Troubleshooting

Use logging

MailBee.NET Queue can log all the activities in log files. These logs are very detailed and can help you discover why the issue you're experiencing occurs.

Control Panel of MailBee.NET Queue provides all the controls needed for enabling, clearing or viewing the log.

Check sending e-mail using another SMTP client

If e-mails are not being sent, make sure you can send them using another e-mail client like Mozilla Thunderbird. It's important for that mail client to be installed on the same machine as MailBee.NET Queue and to use exactly the same SMTP settings. Do not use MS Office Outlook because it's usually configured to send e-mails via MAPI rather than SMTP.

Sometimes, however, the fact that you can send with Outlook Express does not prove there is a problem in MailBee.NET Queue since many firewalls may allow outbound connections for well-known applications like Outlook Express but block connections made by other applications (like MailBee.NET Queue).

Typical problems and solutions

E-mails cannot be sent to external domains. Enable SMTP authentication in MailBee.NET Queue.
Connection with the SMTP server cannot be established on port 25. The server may be SSL-only (port 465), listen to port 587 instead of 25, or port 25 is simply blocked by firewall.
Connection with the SMTP server cannot be established on port 465. The server is SSL-only while MailBee.NET Queue tries to connect to this port as if it were a regular non-SSL port. Set the appropriate SSL mode on SMTP tab of MailBee.NET Queue Control Panel.
Some e-mails could not be sent but they can be sent a bit later (if retried). You've probably reached the allowed throughput limits of your server (for instance, tried to send more than 5 e-mails per session if this server allows no more than 5 e-mails per session). In MailBee.NET Queue Control Panel, adjust the appropriate parameters (like Max E-mails per Session) accordingly the limits imposed by your server. You can read more on these parameters in Using MailBee.NET Queue Control Panel (SMTP Tab) or in MailBee.NET Objects documentation (MaxConnectionCount, MaxSendPerSessionCount and PauseInterval properties of SmtpServer object).
E-mail delivery issues (i.e. e-mails are being sent successfully but still not received by end recipients). Usually, this means your e-mails end up in Spam folder of end users' mailboxes. Make sure your SMTP relay has all the DNS records assigned including valid MX, PTR, SPF entries. Sign your e-mails with DKIM or DomainKeys signatures (MailBee.NET Objects supports both). Try to change the IP address of the sending server (your IP address could get blacklisted).
E-mail submission to the server interrupts in the middle or takes minutes to complete. This most often occurs with MS Exchange servers which support CHUNKING extension for better performance but in fact work slower or do not work at all when CHUNKING is being used. Disable chunking on SMTP Tab of MailBee.NET Queue Control Panel.
The license key stored in the registry (for instance, the key generated by "Get a Trial Key" tool) does not work while the same key stored in app.config or MailBee.NET Queue Control Panel works. This is either permission-related issue (the application can't read certain branch of the registry) or virtual registry conflict. Vista and newer OSes can use different registries for different types of applications (or even for the same application which is being run in different contexts - with admin privileges or normally). This results in "not seeing" by MailBee.NET Queue the license key written by another application in the registry branch with the same name (because they are in fact different branches). If you can't overcome registry issues, you can save the key in app.config unless you need to hide the key to prevent its unauthorized distribution. If you need to hide the key, you can hard-code it in the MailBee.NET Queue code (you can do this because MailBee.NET Queue ships with the source code).
If getting "The service could not be started. Cannot start service MailBee.NET Queue on computer '.'. The service did not respond to the start or control request in a timely fashion." error, you may increase the timeout of starting MailBee.NET Queue Windows service to 60 seconds (from the default value of 30 seconds). Read more at A service does not start, and events 7000 and 7011 are logged in the Windows event log.

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