Photobox, the online photo printing company, is reviewing its European advertising account.
Who Wot Why won the business as a project in 2018 and is not repitching.
The process is being handled by Ingenuity and chemistry meetings took place this week.
It follows Photobox's appointment of Eight&Four to handle the brand's pre-Christmas media and creative activity in 2019.
A spokesman said: "Photobox are looking to find an agency partner that can help them from a strategic and creative point of view across all their European markets. They’re are looking for an agency partner to create a clear and consistent brand platform.
"Ingenuity London is helping the online retailer with agency selection and they are currently in the process of meeting agencies for chemistry sessions."
Charles Faircloth, client partner at Who Wot Why, said: ‘‘We’re proud of the project-based relationship we've had with Photobox over the last few years, but as they restructure and take their priority focus outside of the UK to agencies on the ground in mainline Europe, it feels like an appropriate moment for us to part."
Who Wot Why created an ad for Photobox called "Very important people" that highlighted the reactions of those who receive a photo gift.
Before Who Wot Why, Photobox’s advertising was handled by Creature. The Specialist Works won the Photobox media planning and buying account in 2018.
Mark Singleton is Photobox's top marketer, having joined as chief marketing officer in 2017 from Paddy Power Betfair.
Photobox launched in 2000 and operates in about 10 markets across Europe. It has offices in London and Paris.