Marketing Cloud Email Subject Line Personalization Guidance:
As of January 30, 2026, the email subject line double evaluation feature is deprecated for new customer adoption. On March 15, 2026, email subject line double evaluation will be disabled for all existing customer accounts. Subject lines must be updated by March 15, 2026 to maintain expected functionality.
What is changing about email subject line personalization?
Salesforce is deprecating double evaluation in subject lines. As of January 30, 2026, this feature is deprecated for new customers, and on March 15, 2026, it will be disabled for all accounts.
To ensure that your email campaigns function as intended as they make these changes, a new AMPscript string has been introduces:
%%__SINGLE_RESOLVE%%
How to Use It:
Append this string to the end of your subject line to enforce single resolve:
%%=TreatAsContent(SubjectLine)=%% %%__SINGLE_RESOLVE%%
-or-
%%=v(@SubjectLine)=%% %%__SINGLE_RESOLVE%%
What It Does:
When the platform sends the email, it will remove this AMPscript string and resolve the subject line only once.
After Enforcement Date:
After March 15th 2026, single resolve will become the default platform behavior for all subject lines. At that point, this string will no longer be necessary and can be removed or left in place.
Important Note:
This string only works in the subject line. If used elsewhere, it will appear as plain text in your content.
Here is the page with more detailed information -
https://help.salesforce.com/s/articleView?id=000391994&type=1
#TrailblazerCommunity #Marketing Cloud #Email Marketing #Marketing Cloud Engagement #MarketingCloudEngagemet #Ask An Expert #MCAE
