Campaigns - Hard bounces for valid email addresses

Question

I am getting hard bounces with 'Bad Mailbox Destination Address' for valid email addresses that everybody internally and externally can email without problem.
Doesn't instill me with much faith for sending out 10,000 emails next week!

Answer 1

If you can email that address manually from a regular email address and it goes through fine then it's likely you might be getting blocked by spam filters although usually that would be indicated in your bounce message.
Is your site fully hosted on BC (ie - with BC's nameservers) or is your domain hosted via an A record to point to BC?  If you are being blocked by spam filters then you are likely using the A record because fully hosted sites on BC have the SPF records in place.
If you are using an A record to point to BC's servers for your domain and manage your DNS records somwehere then you need to add a TXT record with the SPF data.  Goto your domain registrar and manage your DNS entries.  You'll want to add a TXT record with the following info:
Record name: @
Record type: TXT
Record value: v=spf1 mx include:worldsecuresystems.com ~all
Record TTL: 86400
You can only have one SPF record on your domain so if you already have a TXT record with SPF data in it for other email services your domain uses (like gmail) you just need to update your TXT SPF record and add "include:worldsecuresystems.com" after the first "include" statement in the TXT record the TXT value would look like:
"v=spf1 mx include:_spf.google.com include:worldsecuresystems.com ~all"
If your problem is that your emails are blocked by spam filters that should fix it but I'm pretty sure 'Bad Mailbox Destination Address' usually indicates a non-existent or malformatted username in your email address (ie - the part before the "@").  I would also double check your subscribers list and make sure there are no spaces or any other invalid character in the email addresses for the customers that are getting bounced back.
Here's more information about your specific error from http://technet.microsoft.com/en-us/library/bb232118(v=exchg.80).aspx which has to do with MS Exchange server specifically but still provides a good explanation:
5.1.1
Bad destination mailbox address
This failure may be caused by the following conditions:
The recipient e-mail address was entered incorrectly by the sender.
No recipient exists in the destination e-mail system.
The recipient mailbox has been moved and the Microsoft Office Outlook recipient cache on the sender's computer has not updated.
An invalid legacy domain name (DN) exists for the recipient mailbox Active Directory.
This error typically occurs when the sender of the message incorrectly enters the e-mail address of the recipient. The sender should check the recipient's e-mail address and send again. This error can also occur if the recipient e-mail address was correct in the past but has changed or has been removed from the destination e-mail system.
If the sender of the message is in the same Exchange organization as the recipient, and the recipient mailbox still exists, determine whether the recipient mailbox has been relocated to a new e-mail server. If this is the case, Outlook may not have updated the recipient cache correctly. Instruct the sender to remove the recipient address from sender's Outlook recipient cache and then create a new message. Resending the original message will result in the same failure.
Other issues may cause this error, such as an invalid legacy distinguished name (DN) in Active Directory. Examine and correct the legacy DN of the recipient's mailbox. Then instruct the sender to remove the recipient address from sender's Outlook recipient cache and then create a new message. Resending the original message will result in the same failure.