I cannot send email, what are the possible causes and solutions? 

1. You may be sending on the wrong port, it is possible that your ISP blocked the old standard port 25.

• The settings for this will be different depending on which mail client you use.
• This article will explain the issue in greater detail.
• Old mail clients default to port 25. This is by far the most common issue stopping users from sending email.

2. If you are receiving a 533 error when attempting to send, this article will help address that.

3. If your emails are going out, but you are receiving a bounceback message then it is likely an issue on the recipient's end. The only thing you can do is alert the recipient and let them know that their antispam settings are making them lose real email.

• This article will further explain this issue.

4. Your domain name may not be pointed correctly. This article will help you run a WHOIS check to make sure that your domain is pointed properly.