Monthly Archives: December 2009

Google Apps: One button to merge all duplicate contacts

As Google Partners we love to see the adoption of Google Apps and we love to see all of the updates!

Managing a big address book can be a challenge, so it’s no surprise that the top request for Google contacts is a fast, easy way to merge duplicate contacts. You’ve been able to merge contacts one-by-one for a while, but now we’ve added a single button that merges all your duplicate contacts at once. To clean up your contact list in one fell swoop, just click the “Find duplicates” button in the contact manager, review the merge suggestions (and uncheck any suggestions you don’t want merged), and hit the “Merge” button.

If you’ve been considering getting all your contacts into Gmail or syncing your Gmail contacts to your phone, now’s the time to do it. As we’ve written about previously, you can sync your contacts to a wide variety of devices (including Android, iPhone, Blackberry, SyncML, etc). So if you were dreading spending hours getting your contacts in order, now you can do it with a couple clicks.

For more details, go here.

Reverse DNS FAILED! This is a problem.

When a sending server makes a connection to the recipient server, the recipient server notes the sending IP address and performs a reverse lookup.  This is done by sending a DNS query which returns a Fully Qualified Domain Name ( FQDN) registered for that IP address.  If the sending SMTP address matches the domain, then it’s much more likely that the message is legitimate and therefore will be passed on to the recipient.  If the IP address doesn’t match, it’s much more likely that the sending address was spoofed and therefore much more likely that it’s unwanted and could be considered spam.

A FQDN is associated to an IP with a valid PTR record. You want the domain name portion of the FQDN to match the domain of your email address. (e.g. if your sending addresses follow the convention of, your PTR record should contain something like Only the organiztion which controls and owns the IP can set a PTR record. PTR record queries are sent to the owner of the IP address which is the ISP, unlike other DNS queries which are sent to the DNS server of whoever owns the domain. For this reason Setting a PTR record on your own DNS servers is almost useless since no one is asking your servers.

CSMA Blacklist – Website Down

UPDATE 12/3/2010: It appears that the CSMA Blacklist is officially going offline. They have updated their website with these details:

Notice: Due to name server configuration issue, DNS traffic was temporarily rerouted to a server that provided improper results. The problem was resolved, however some lookups may return incorrect information for the next several hours. Please check back later if you are still having problems. NOTE: This list is scheduled to be deactivated and should no longer be used in active production.

My Engineers are currently working on removing that Blacklist from our tool as it is no longer a valid list.


We have received reports that the RBL (Real Time Blacklists) CSMA has gone down.  My Engineers have completed an investigation and they discovered that the RBL CSMA isn’t dead, but their website is offline at this time. Please view the Google Cache of their website for more details. Our tool is working as it should however it appears that CSMA is having technical difficulties on their end.

MxToolBox is not affiliated with any Blacklists, we just provide a public tool that can be utilized to see if you are on a Blacklist. If you are on a Blacklist, rest assured as we do offer Blacklist Protection! For more information please feel free to visit our website or email us at

For more information on what Blacklists are and how MxToolBox can help, read this blog post. We’re always looking for new Blacklists to add, so if you want to suggest one to us, please send an email to

For information about other Blacklists that have shut down or Blacklists that are having problems, view this forum post.