1. Your carrier has a network outage. The messages may arrive hours late. You need to call them for status and wait a while (days) for this to clear. Fortunately, this should not happen very often, perhaps once a few months.

2. Your carrier has been blocked from sending out messages because other users sharing the same outgoing route has been sending SPAM. It typically takes a few hours to clear. You may have received the following message:

FRM:Admin

SUBJ:Error Msg not delivered

MSG:Each of the following recipients was rejected by a remove mail server.

The reason given by the server are included to help you determine why each recipient was rejected. Recipient (web@db4.us) Reason: Junk mail rejected (schemailmt107.cingular.com ) 209.183.132.185 is in an RBL see http://www.spamhaus.org/query/bl?sp=209.183.32.185

3. Phone carriers may block your incoming messages if you receive too many from the same source, such as db4.us . If you have received messages from one source for a while (days) and noticed the messages stop coming, you may need to talk to your phone carrier support to re-enable the incoming messages.

For AT&T, they have provided the following web site for customers to login and "allow" email addresses to send incoming messages: