Translating an email subject line is a choice about meaning, not a character-matching exercise. A phrase that feels natural in one language may become vague, formal, or too long in another. Preserve the campaign's useful promise, pair the subject with its preview text, and test what the inbox actually displays before trying to make every version the same length.
Define the promise before translating
Write down the message's factual core: a product returned, a guide answers a question, or a real offer ends at a specific time. Keep those facts unchanged while allowing the sentence structure to adapt.
Avoid idioms that depend on a pun or cultural reference unless a capable reviewer can produce an equivalent meaning. A plain subject is often a stronger starting point for several languages than a clever phrase that only works in one.
Translate the reason to open first
Take the message “The linen shirt in your selected size is available again.” Its useful facts are the product, the relevant size, and renewed availability. A language reviewer can reorganize those facts naturally. An alternative that becomes “Your favorites are waiting” may be shorter but loses the specific reason the recipient requested the update.
Give the reviewer both the factual promise and the audience context. If the recipient asked for a particular restock, a direct availability statement makes sense. If the campaign goes to all subscribers, do not imply that every recipient requested or previously wanted the item. Good localization preserves the relationship as well as the product facts.
When an offer condition cannot fit comfortably in the subject, avoid a broader claim that becomes misleading without it. “Selected sets: 15% off” is different from “Everything is 15% off.” The preview and body can explain the full terms, but they should not be needed to reverse the subject's apparent promise.
Use preview text to support the local subject
In each Sendvio language version, write the preview as a useful continuation rather than a repeated translation of the subject. Check whether the most important information appears early enough to survive a shorter inbox display.
Do not remove essential conditions simply to fit a visual target. The email body must state them clearly regardless of how much preview text appears. Dates, currency, and time zones need special attention when the offer spans markets.
Read the first visible words without the rest
Inbox display varies with the app, screen width, sender name, and user settings. Instead of chasing one character count, inspect whether the opening phrase communicates the main point when the ending disappears. Avoid placing an essential product distinction after a long greeting or a decorative introductory phrase.
For a product guide, the subject might identify the question and the preview explain what the reader will learn. For a deadline reminder, the subject can name the actual offer and the preview give its timing. Treat the pair as two useful pieces of information, while ensuring neither assumes the other will always be visible.
Test a version with no first name and one with a long name. If personalization pushes the useful part beyond the visible area, reconsider whether the greeting belongs in the subject. A short, specific message without a name can feel more relevant than a generic promise preceded by a personalized greeting.
Test in context
Send tests and inspect the sender, subject, and snippet together. Check long personalization values and missing fields. A subject that looks acceptable alone may feel crowded beside a long sender name.
Review performance by language without assuming differences prove the translation is better or worse. Audience size, product availability, and market familiarity also matter. Use results to identify a question for review, then improve the actual wording rather than applying a universal shortening rule to every language.
If a language version performs poorly, inspect clicks and downstream behavior alongside delivery and available open data. An inbox-display issue is one possible explanation, not the only one. Compare messages with similar audiences and purposes, and keep a note of the wording decision you are testing so the next revision answers a specific question.