This problem has a number of common causes. Generally, unless you've received an announcement from us that mail isn't working properly at the time you're having difficulty, chances are that it is one of those common issues.
ISPs often block the outgoing mail port in an effort to force their users to use their own email servers. They sometimes do this without warning and sometimes even intermittently.
If your ISP isn't the cause of your sending problem, you may not have authentication turned on in your email client. Not having authentication turned on can cause email to work fine one day and suddenly stop working the next. If you turn on authentication, you should see the problem disappear.
If neither of these solutions works for you, please open a ticket at our Customer Portal and we will gladly take a look at the problem. One of our able technicians will gladly help you with any related issues and help your resolve your problem. abdicar.com is widely known for it's customer service and technical support.