Starting February 21^st 2023, Salesforce Marketing Cloud will stop processing nested AMPscript within email subject lines. The change comes as a result of Salesforce’s efforts to provide more efficient and secure processing of customer data. With this change, the subject line will treat any nested AMPscript as content — similar to how AMPScript is processed in the email body today.

Source: https://help.salesforce.com/s/articleView?id=000364408&type=1

What does this mean exactly?

Currently, upon sending an email, Marketing Cloud processes the subject line twice in order to evaluate any nested variables and nested AMPscript, which is often used for advanced personalization.

Let’s go through the following example.

In the email, inside the subject line box, you are using the v() function to display the content of the @subject variable:

The @subject variable is defined inside the email body and it’s set up to take the recipient’s first name from a Data Extension:

%%[
var @lookupValue, @firstName, @subject
set @lookupValue = AttributeValue("_subscriberkey")
set @firstName = Lookup("Recipients","FirstName","SubscriberKey", @lookupValue)
set @subject = "%%=v(@firstName)=%%, only the best deals for you!"
]%%

On send time, Marketing Cloud will first resolve the subject in the subject line box, which will result in:

Subject: %%=v(@firstName)=%%, only the best deals for you!

And then, it will process it for the second time, which will result in resolving the nested @firstName variable and picking the recipient’s name from a Data Extension, as intended in the script inside the email body:

Subject: Zuzanna, only the best deals for you!

Above is a quite simple and common use case for subject line personalization, but there are many other, more complex options, such as the one outlined by Eliot Harper and Greg Gifford in this Salesforce Stack Exchange post:

Again, in the email, inside the subject line box, we are using the v() function to display the content of the @subject variable:

The @subject variable is defined inside the email body and it’s set up to take the subject from a Data Extension:

%%[ 
var @subject
set @subject = Lookup('SubjectLines', 'Subject', 'Email', emailName_) 
]%%

And the @subject value pulled from the Data Extension has a nested personalization string inside it:

Thanks for supporting %%ChildFirstName%%

Marketing Cloud would currently pull the string from the Data Extension on the first pass:

Subject: Thanks for supporting %%ChildFirstName%%

And on the second pass, it would interpret the %%ChildFirstName%% personalization string and grab the correct value from the Sendable Data Extension:

Subject: Thanks for supporting Anna

After February 21^st 2023, Salesforce Marketing Cloud will stop processing nested AMPscript within email subject lines, which means that the two subject lines from the above examples would resolve to:

Subject: %%=v(@firstName)=%%, only the deals best for you!

Subject: Thanks for supporting %%ChildFirstName%%

and would not be further processes.

How to proceed in case you already have emails with nested AMPscript/personalization strings?

Salesforce Marketing Cloud users will need to update their email subject lines to personalize using a single AMPscript call without nesting variables or functions by February 21^st 2023.

There are a few different approaches to making sure that your subject lines will work as intended after the change comes to life, all of them are described in the original help article, but the two I found most useful are the following.

Solution #1: Avoid the v() function in your @subject variable

Let’s revisit our first subject line example. In the email, inside the subject line box, you are using the v() function to display the content of the @subject variable:

And the @subject variable is defined inside the email body and set up to take the recipient’s first name from a Data Extension:

%%[ 
var @lookupValue, @firstName, @subject 
set @lookupValue = AttributeValue("_subscriberkey") 
set @firstName = Lookup("Recipients","FirstName","SubscriberKey", @lookupValue) 
set @subject = "%%=v(@firstName)=%%, only the best deals for you!"
]%%

The solution to correctly outputting the subject line after the Feb’23 change would be to replace the v() function used inside the @subject variable in the email body with a concat() function:

%%[  
var @lookupValue, @firstName, @subject  
set @lookupValue = AttributeValue("_subscriberkey")  
set @firstName = Lookup("Recipients","FirstName","SubscriberKey", @lookupValue)  
set @subject = Concat(@firstName, " only the best deals for you!")
]%%

That way, the whole AMPscript would be already processed inside the email body and the @fisrtName variable used inside the @subject variable would be already resolved once the subject reaches the actual subject line, giving us:

Subject: Zuzanna, only the best deals for you!

Solution #2: Using the TreatAsContent() function to force the subject line to fully render on the first pass

Let’s now revisit Eliot’s and Greg’s example.

In the email, inside the subject line box, we are using the v() function to display the content of the @subject variable:

The @subject variable is defined inside the email body and it’s set up to take the subject from a Data Extension:

%%[  
var @subject 
set @subject = Lookup('SubjectLines', 'Subject', 'Email', emailName_) 
]%%

And the @subject value pulled from the Data Extension has a nested personalization string inside it:

Thanks for supporting %%ChildFirstName%%

The solution to correctly outputting the subject line in this case, would be to replace the v() function used inside the subject line box in the email editor with a TreatAsContent() function:

%%=TreatAsContent(@subject)=%%

That way, the whole AMPscript contained in the email body and any additional variables and personalization strings maintained in the Data Extension can stay exactly as they were, and you only need to change from the v() function to the TreatAsContent() function in the subject line box inside your email.

This option is by far more convenient in case you already have a lot of advanced personalization in place in your emails.

Considerations

• The above examples are just a couple of common use cases, but be aware that there are countless variations of nested AMPscript in subject lines, so make sure to fix and test each email on a case-by-case basis.
• You only need to fix emails that you are currently using or intend to use in the future. If you created and sent a one-off email last month and don’t intend to use it in the future, you don’t need to change the subject line.
• Triggered sends (and therefore Journey Builder emails) do not pick up email changes until they are republished. So if a triggered send email is impacted, you need to fix the email AND republish the appropriate triggered sends. To learn more about triggered send, see here.
• Pre-headers are treated as part of the email body and will not be impacted by this change. To learn more about personalising preheaders (which differs from personalizing subject lines), see this help article.

Sources:

• https://help.salesforce.com/s/articleView?id=000364408&type=1
• https://salesforce.stackexchange.com/q/379481/50456

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Questions? Comments?

Leave a comment below or email me at zuzanna@sfmarketing.cloud.

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