I’m having trouble with my Python code that sends emails through Gmail. The script works on some hosting providers but fails on others. Here’s what I’m using:
import smtplib
email_content = 'Test message from Python'
mail_server = smtplib.SMTP('smtp.gmail.com', 587)
mail_server.ehlo()
mail_server.starttls()
mail_server.ehlo()
mail_server.login('[email protected]', 'password123')
mail_server.sendmail('[email protected]', '[email protected]', email_content)
mail_server.quit()
When I run this on different web hosts, I get mixed results. One host throws a connection refused error, while another seems to process everything normally but the email never arrives. The debug output shows successful SMTP responses including authentication and message acceptance, but recipients don’t receive anything. Could this be related to hosting provider restrictions or firewall settings blocking outbound SMTP connections?
Yeah, this is definitely a hosting provider issue. Most shared hosts block ports 587 and 465 to stop spam - that’s why you’re getting connection refused errors. When authentication works but emails vanish, your host is probably intercepting SMTP traffic or routing it through their own servers with extra filtering. I’ve hit this before and switching to your host’s local SMTP server usually fixes it. Most providers have their own mail relay services you can use instead of Gmail’s SMTP. Check if your host requires their authenticated SMTP service or has whitelisting for external SMTP servers. Also common - some hosts mess with outbound email headers or need SPF/DKIM authentication that Gmail’s SMTP doesn’t provide in the format they expect.
This screams port blocking or SMTP filtering by your host. I’ve hit the same wall before - many providers do silent filtering where everything looks fine but your emails just vanish. Some hosts force you to authenticate through their mail servers first or only allow whitelisted SMTP services. Your host’s IP reputation might be trash too. Gmail accepts it, but other servers downstream reject it. Make sure you’re sending proper Message-ID and Date headers since some hosts mess with these. Try a telnet test to smtp.gmail.com on port 587 - that’ll tell you if it’s a connection problem or just policy blocking.
I’ve dealt with this exact problem. Use app passwords instead of your regular Gmail password if you haven’t tried that yet. Google killed less secure app access, so normal passwords won’t work anymore. Also, some hosts force you to use their SMTP relay even for Gmail - check your cPanel or hosting docs for any SMTP restrictions they’ve set up.