I’m having trouble with my .NET application that sends emails using SMTPClient. For some reason Gmail and Hotmail are marking these emails as spam.
I’m using an authenticated account on my local server which has an SPF record set up. My hosting provider (gogrid) isn’t sure what else to do.
The weird thing is that only emails from my app get flagged. If I send emails through the same SMTP server using other methods like squirrelmail they come through just fine.
I’m thinking there must be something these other email tools are doing that I’m not. Has anyone run into this before? Any ideas on how to fix it?
Here’s a simplified version of my code:
using System.Net.Mail;
var message = new MailMessage();
message.From = new MailAddress('[email protected]');
message.To.Add('[email protected]');
message.Subject = 'Test Email';
message.Body = 'This is a test email from my app';
var client = new SmtpClient('smtp.myserver.com', 587);
client.Credentials = new NetworkCredential('username', 'password');
client.EnableSsl = true;
client.Send(message);
Any help would be much appreciated!
I encountered a similar issue with my .NET application. One often overlooked factor is the sending IP reputation. If your server’s IP has been used for spam in the past, it could be blacklisted. Consider using a dedicated IP for sending emails or a reputable third-party email service provider.
Another aspect to check is the consistency of your ‘From’ address. Ensure it matches the domain you’re sending from. Also, gradually increase your sending volume to build a positive reputation with email providers.
Lastly, implement proper email authentication protocols like SPF, DKIM, and DMARC. These significantly improve deliverability and reduce the chances of your emails being marked as spam.
I’ve dealt with this exact problem before. One thing that helped me was adding proper headers to my emails. Try including List-Unsubscribe and Message-ID headers. Also, make sure your email content isn’t too HTML-heavy or filled with spammy keywords.
Another trick is to use Domain Keys Identified Mail (DKIM) signing. It’s a bit of a pain to set up, but it really improves deliverability. You might also want to check if your IP is on any blacklists - there are online tools for that.
Lastly, consider using a transactional email service like SendGrid or Mailgun. They handle a lot of the spam-avoidance stuff for you and can significantly boost your delivery rates. It saved me tons of headaches in the long run.
maybe check ur email headers? sometimes weird stuff in there can trigger spam filters. also, try adding DKIM authentication if u haven’t already. that helped me when i had similar issues. could also be the content - if its too salesy or has lots of links, that might set off alarms. gl fixing it!