Fix "552 5.7.0": The attachment was rejected (type or size)

Bouncing with 552 5.7.0? It means the attachment was rejected (type or size).

How to fix it

Remove blocked attachment types or link to files instead.

Prevent it

• Authenticate with SPF, DKIM and DMARC.
• Send from a dedicated IP.
• Keep bounce and complaint rates low.

How Rainmail helps

Rainmail sends from your own domain on a dedicated, isolated IP with SPF, DKIM, DMARC, reverse-DNS and managed warm-up handled for you, plus a REST API and an AI watching deliverability — and it welcomes senders SES, SendGrid and Mailchimp reject, from $8. Run the free checker or see plans.