You used to be able to use Gmail, but now you can't. What do you mean by this? I didn't understand the first part of your query.
If this indicates that it was previously working and has now stopped without any changes, check it using a different network. It's possible that your network is preventing access to the Gmail servers.
However, for testing purpose you can use Papercut which supports SMTP (send email). refer the documentation for more details
Hi Adnan Avsar,
The email connector works well with the gmail account. For more information you can refer below documentation for the details.
For testing purpose you can use smtp diag tool also. Refer below link for details
https://adminkit.net/smtp_diag_tool.aspx