How AJO constructs Email Mirror Page URLs and related length limits?

[ChrisMagnemi]

My team and I have encountered this error a couple times now - Some larger emails with more personalization have mirror page URLs that are too long to function properly, with the error message that the length surpasses the supported character limit.

Adobe seems to be working on a solution to extend this mirror page url character limit beyond the approx ~4000 character limit, though its not clear when that will happen. Still I'm curious how exactly AJO constructs that mirror page url, especially so we can plan around it until the limit is extended.
Roughly, it seems like personalization attributes within the email content are hashed and then stored in that url? But I believe there's also some kind of signing that happens, and/or maybe other processes?

Any info about how AJO constructs email mirror page URLs and the factors that contribute to its length would be greatly appreciated!

[SatheeskannaK]

@ChrisMagnemi Take a look at this documentation page,

https://experienceleague.adobe.com/en/docs/journey-optimizer/using/channels/email/design-email/add-c...

It's good that you already brought up the issue with Adobe and they're working on an enhancement request.

[DavidKangni]

@ChrisMagnemi 

Mirror pages links are auto-generated and cannot be edited. They contain all the encrypted personalized data that is required to render the original email. As a result, using personalized attributes with large values may generate lengthy mirror pages URLs, which can prevent the link from working in web browsers that have a maximum URLs length.

That being said three parameters (plus configId and timestamp) will be included into the mirror page generation

• params --> contains the encrypted payload
• pid --> encrypted profile ID
• p --> encrypted personalized data
• configId --> configuration ID
• t --> timestamp

https://<subdomain>/ee/v1/webview?
params=v1.483wicnCf_HN5ktTyp74YTQ4LubTbHCRroeNPdbaHi5cQwsRVa3rvGcoP-4ZFfc6zgTsg_niqIxiKc1e6AgY4CX11KjNRFQ15q9yC5kd5zRFg3k1byLEh4jpgsTsucVdpXdywnraLsia8nK586G3h68YbWMKsDNAREPzMEWsGmRI6F6VvHEdd_Y3YmyCJhIykNldH_-aA2r0kzHNbKEZzIpiSAOF5L4_vLGpt1XbFxi6gH2n45A4LiaetybJTlT0wniW5PR5I2sFqNhQw7kM7kD4w3nFVU0uObV59aLghrV98OK8kQVoZgwxFBsy
&configId=a06f1d39-fdc3-41fe-85bf-08066f298482
&pid=v1.ErPGeIAEmqOC_zchfaPnO_KQOuzyJvOTpV88HW_xAxptyev_bf1-2Ryqr4TDshjpUQHOJ8xy9_Dea_9Ar9rlQfnhleoXqrQgqrHbgiibY9CWhYplp0OP9_Ix40ikdy7gCwWor2LlAhI5Z0gULs38kqkTWqffUOgegSB5HWWeGVPV1PiAvxTGGqV0-zdwD7J9H6tQsh5fMFhLoMTGxtLck0vajz5OlIxk

&p=v1.DRnF8KEtkYxZVqIhjTXLQvHABwgxHOZ1eVlGV5RnpZkiefYdWLavqtGLudxT59LaqgwOBLt7sM1TQNGCi5aF_GZxddDzt0YWuLRBdeB5oYQhCYpyHuq3UCdgVBqjtkltr8ZZ-PggOjr-F4ND_nDPSmrFiQREpsGhct18yeziADn46zvAokrXCbh2VUY2GXpDMwmnoNin8sJw-FVdZCMJ8thQdV2gkS6dKwvNIgkldBmO1Tfb4O-Jv22AbaO0isAef3tG7Z4xBlINgu8n9RiwphhplcCEBO398tPeMLXOVjmQsJjJxzsZL2WMfHmZDTI4AZkL7pD-jfYT1d2m5fQSQANRgns0kWbfi92lDGa9I-GbmicRab-cfao2LbGyekpYnpdfUzSjlumDtutwl_wqxZTvFzK62MJpjn2G0bwhM3BleciU9wgWTSYDZ9XWKDar6BGsugcNTudKmYl3nrSlwVCm0SONN0H0oVXrZOUQUdQV_85QL64lxLxM6eWh1TjZurQzZ0wenQEf9dnoQAYEzXXm_LWqJpzRfPxKizc_CEyxsK9XVrunq66uDxr0sZBiuKDeInvlU36UL1sLdSuZHMHMD-Wx1XX1EGfNq2TC8T30iQq9w_HQvCkDs2qBit35Iv2_g93r5BgfDJYT6ZeHxNZJoG8PzBsKv_8yMTmyrFsTJmxT6x0PLrKgdJDdQtEfj5wLX2bLN1pXLKFSaZm6GvpLqLRxDAFo
&t=1758654518451

Thanks,

David

[Mayank_Gandhi]

@ChrisMagnemi 

When you insert a “Mirror Page” (or “View this email online”) link in an AJO email, the system auto-generates a special URL for each recipient that:

• Points to Adobe’s hosted mirror page service.
• Encodes all personalization and context data required to fully re-render the recipient’s unique version of the email.
• Is cryptographically signed and encrypted to prevent tampering.
  
  The URL becomes LONG because every personalization attribute’s value (sometimes many KB in total), plus structural info and tracking metadata, are serialized into the payload and then encrypted (encryption typically increases size by 30-50%). The URL must fit through edge proxies and browsers.Practically, the safe maximum for most browsers is ~4096 characters (4 KB)

Best Practices Until the Limit Is Extended

• Keep personalization minimal for emails where the mirror link must be supported.
• Avoid passing large arrays/objects or full segment membership.
• If necessary, link to a static landing page you control instead of the built-in mirror page.