I’m working with the Mailgun API through PHP cURL requests and need help setting up specific headers for two different email types. I want to make sure my emails are delivered with the exact header configuration I need.
Can someone show me how to structure the cURL request in PHP to include these headers properly? I’m particularly confused about how to pass custom headers through the Mailgun API parameters.
Mailgun’s tricky with headers - some you can override, others they control internally. I hit this when switching from another email provider and learned about their quirks the hard way. For your first email: Mailgun often normalizes the charset in Content-Type during processing. Test heavily to make sure iso-8859-1 actually sticks. Second config: Be careful with custom Message-ID formats. Yeah, it’s possible, but it can mess with Mailgun’s tracking and analytics if your format doesn’t match what they expect. One more thing - with multipart emails, your boundary parameter needs to be unique AND match exactly what’s in your message body. I’ve seen mismatches cause silent delivery failures that were a nightmare to debug.
I’ve hit this exact issue before with custom Mailgun templates. Here’s what I learned: Mailgun auto-handles some headers but others need explicit setup. For your first email - use the standard ‘from’ parameter in your cURL data, not as a custom header. Content-type and Content-Transfer-Encoding go in as custom headers with the h: prefix. Your second email’s trickier since it’s multipart. Mailgun auto-generates MIME-Version and Message-ID, so you’ll get conflicts trying to override them. I had better luck letting Mailgun handle Message-ID - helped with deliverability. Reply-To definitely needs the h: prefix. For multipart boundaries, your actual email content has to match whatever boundary you set in Content-Type or Mailgun will reject/reformat the message. One gotcha that bit me - some headers like MIME-Version are protected by Mailgun’s system. Test everything to make sure your custom values actually show up in delivered emails.