When it comes to sending email attachments, file size matters more than you might think. Too small, and you risk sending low-quality content that doesn’t impress. Too large, and your email might never make it to its destination. Just like the perfect porridge- what you want is something just right—the Goldilocks zone of email file sizes.
Let’s talk about why that balance matters, and how to find it.
Why File Size Can Make or Break Your Email
Email might feel instant and seamless, but behind the scenes, there are strict rules, limits, and filters that decide whether your message gets delivered—or disappears into the abyss.
Sent a file that’s too large?
You could hit the dreaded bounce. Or worse: your recipient’s server might reject your email altogether without letting you know. Many popular email providers impose limits anywhere between 10MB to 25MB on incoming attachments. That means if your file tips just slightly over their limit, it’s game over. The tricky part? There are no hard and fast rules—limits vary by provider, and they can change without warning.
Sent a file that’s too small?
Compression can be useful, but overdoing it can sabotage the quality of what you’re sending. Think grainy images, distorted PDFs, or videos that look like they were shot on a flip phone from 2003. Not exactly the professional look you’re going for.
So, What’s the “Just Right” Size?
There’s no universal answer—but there is a sweet spot.
At SMTP2GO, we support attachments up to 50MB per email (including the message content), which gives you more flexibility than many traditional providers. But that doesn’t mean you should always max it out.
Here’s a good rule of thumb:
Under 5MB – Ideal for small documents, light images, and quick reads.
5–15MB – Great for standard presentations, PDFs with images, and higher-quality visuals.
15–25MB – Use with caution. Large files can still fail if your recipient’s server has stricter limits.
25–50MB – Best reserved for internal use or situations where you know the recipient can handle it.
Whenever you’re sending files near the upper limit, consider using cloud-sharing links (like Tresorit) instead. It’s more reliable and plays nice with inbox filters.
Quality vs. Deliverability: A Delicate Balance
Every email you send is a balancing act between quality and deliverability. You want to make an impact, but not at the cost of actually getting your message through.
Here are a few pro tips:
Optimize your images – Use compression tools that reduce file size without wrecking quality.
Avoid zipping everything – Some email servers see zip files as suspicious and may flag or block them.
Stick to common file types – PDFs, JPEGs, and DOCX files tend to be safer and more widely accepted.
Even the Three Bears Would Approve
Email attachments aren’t one-size-fits-all, but finding that just right spot doesn’t have to be a guessing game. With SMTP2GO, you get generous attachment limits, smart delivery tools, and a support team that’s always ready to help. Whether you’re sending polished presentations or content-heavy newsletters, we make sure your emails land where they’re supposed to—no bounces, no surprises.
Sign up for a free trial or reach out to our award-winning support team to get started.
