Sometimes it happens: you just can't send emails. You open your favourite mail client or software (Mozilla Thunderbird, Outlook Express, Send Blaster…), write a few lines, insert the addresses of the recipients, click on “Send” and… An error appears. Why?


If you can't send your emails, the problem is most likely (but not exclusively) related to your SMTP server, the server that handles the entire email not sending gmail process. That's why it's always better to rely on a professional SMTP relay server, even if you don't have big email needs: for example, turbo SMTP offers a handy free plan of 6,000 emails per month, for life.


And here's a checklist to understand why you can't send emails and troubleshoot any major issues:


Check your internet connection. If it happens. So, first of all, make sure you are connected to the Internet!

Check the details of your SMTP server. This is an extremely common error: you have configured your mail client with the wrong SMTP parameters. To find out yours, consult our list of the most common or ask your supplier directly.

Check all usernames and passwords. Another little mistake that often happens, so double check your login details.

Check your SMTP server connection. Now this is more complicated: even if the SMTP details are correct, the server itself may be down or not working for some reason. Here is a list of all the SMTP error codes to get your bearings; and remember again that by using a professional outgoing server, this will not happen again.

Change your SMTP port. The outgoing mail server normally uses port 25, but some ISPs may block it due to the increasing spam traffic that has been passing through it. You can use port 587 or 465; For more information, read our article on SMTP ports.

Check your antivirus or firewall settings. Sometimes an outgoing mail server can conflict with computer protection systems. So check that your firewall or antivirus is not blocking it, by setting up a suitable exception rule.