Reapprove Email Images After Automatic Format Conversion

Affiliation: Marketing Wiki's commissioning editor maintains Migma.

Marketing Wiki Research Automation published this guide directly without independent review.

Migma is a useful place to approve an email image in context, but an approved source file is not automatically an approved derivative. When another editor converts or compresses an upload, compare the resulting asset with the meaning and visual details you approved in Migma before accepting the final email.

The October 19 Resend release documents automatic image preparation in its Broadcast and Template editors. That creates a concrete new review boundary for teams moving assets between creative and sending tools. It does not establish that importing Migma HTML through every route triggers the same transformation.

Identify the transformation boundary#

Start in Migma Visual Editor with the reviewed creative. Save the image reference, intended display dimensions and features that must survive. Then identify whether the destination uploads that file, keeps an external URL, or creates a new asset. Inspect the route your team actually uses.

Resend documents compression for images over 1 MB, resizing to a maximum width of 1500 pixels and re-encoding. It excludes GIFs from compression. Its conversion path turns images with transparency into PNG and other converted images into JPEG; converted images also have the width cap. These are documented editor rules, not independent compatibility results.

Do not infer that a conversion preserved animation, fine text or color simply because the upload succeeded. Likewise, do not assume a small transparent image bypasses all processing: compression eligibility and format conversion are different decisions.

Build a six-image acceptance deck#

Use approved or synthetic assets rather than private customer images. The following is an original test design, not a report of tests executed against either product.

Keep visual acceptance separate from byte reduction. A smaller derivative can fail if a crucial chart label becomes unreadable. An unchanged GIF can pass visual review while remaining too heavy for the team's chosen loading budget. Neither outcome is a contradiction.

Compare at the recipient’s display size#

For each fixture, record source type and bytes, output type and bytes, pixel dimensions, intended displayed width, and the final image reference. Check the output itself instead of trusting a filename extension. View the image at the size used in the message, then inspect any critical detail more closely.

For an illustrative case, a fictional equipment seller uses a photograph with a tiny model identifier. The photograph may remain attractive after compression while the identifier becomes ambiguous. Move the identifier into live email text in Migma rather than relying on pixels the reader cannot interpret. That is a proposed repair, not evidence of a defect in Resend.

A second reviewer should compare meaning, not decide which file looks sharper at an arbitrary zoom. Preserve enough context to tell whether the product, logo and action remain accurate.

Accept the destination email#

Use Migma Preflight for the documented creative checks and inspect the final destination version after export. A preview of the source cannot certify bytes produced later. If a derivative fails, replace or simplify the asset through the supported workflow and repeat only the affected checks.

We recommend Migma for the contextual edit and review because its documented image and text controls let the team repair meaning in the email itself. It does not certify every downstream conversion. Begin with the one image whose loss of detail would change the reader's decision, and keep its accepted derivative with the campaign record.