Common reasons why you can't send emails using your mail client
There can be many reasons why you are unable to send emails. If you cannot receive or send emails, please check your Internet connection, make certain that all the details are correct in your mail client (including user name, password, and mail servers), see whether or not your mailbox is full, or review the status of your domain name.
If you can receive emails, but not send emails, try the following steps:
The emails you send
If your emails are coming back to you rather than being sent, check that you have the email address in the To: field correct. Or if you have attached files to the email, make certain they are smaller than 20MB, as our attachment limit is 30MB and adding files to an email causes the file size to increase.
The Outgoing Mail Server
Your Outgoing Mail Server should be mail.[domain], where you replace [domain] with your domain name. So, for example, if your domain is www.thisismydomain.com, your Outgoing Mail Server would be mail.thisismydomain.com.
Your Outgoing Mail Server should be set up to authenticate using your password, and should not be using SSL.
The other software on your computer
If you have a strong firewall or anti-virus program on your computer or network, it may be blocking emails from going out. Try turning it off, sending out a test email, and then turning it back on. If the email can get through, then review the support information given for your firewall or anti-virus program and see if there is a way around it.
Some ISPs block port 25, which is the common port for sending email. Contact your ISP to check, and if they have, try using port 587, which is an alternative.
If none of these are the reason why you cannot send emails, it may be that your IP address has been temporarily blacklisted.