Fix: attachment too large / message size exceeds limit

Seeing "attachment too large / message size exceeds limit"? Here is what it actually means and the specific fix — not generic advice. Most email errors trace back to DNS or an encryption setting, and both are quick to correct.

Quick summary

• Keep attachments well under 25 MB; base64 encoding inflates size ~33%.
• Share large files via a link instead.
• Compress images and PDFs before attaching.
• Send a test message and check it lands in the inbox, not spam.
• In Gmail, use "Show original" to confirm SPF, DKIM and DMARC all pass.

What is happening

The message exceeded the receiver's size cap (commonly 25 MB including encoding overhead).

How to fix it

1. Keep attachments well under 25 MB; base64 encoding inflates size ~33%.
2. Share large files via a link instead.
3. Compress images and PDFs before attaching.

Confirm it is resolved

• Send a test message and check it lands in the inbox, not spam.
• In Gmail, use "Show original" to confirm SPF, DKIM and DMARC all pass.
• If it persists, re-verify your domain in the OquMail dashboard.

Common questions

How long does fix take for a small business?

Most teams finish domain connection and first mailboxes in under an hour. DNS propagation is often minutes; in rare cases wait up to 24–48 hours. OquMail shows live verification so you know when you are ready.

Do I need technical experience to set up business email?

No. If you can log into where you bought your domain and paste a few lines of text, you can set up professional email. OquMail guides you step by step and verifies when DNS is correct.

Can my small team use business email for free?

Yes. OquMail's free plan includes up to 15 mailboxes on your own domain with webmail, guided SPF/DKIM/DMARC setup, and a transactional email API — no credit card required.