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juancarll454986
New Participant
September 16, 2026
Solved

Email trigger on Start Node truncates attachment filenames with underscore (_[number])

  • September 16, 2026
  • 1 reply
  • 35 views

Hi,

We are using a Start Event with a Receive Message trigger configured for Email messages.

When an incoming email contains an attachment named Render_2026091902.pdf, Appian automatically creates and stores the document as Render.pdf in msg!properties.Attachments, completely stripping the underscore and the numeric string.

Testing findings:

  • Render_2026091902.pdf saved as Render.pdf (truncated).

  • Render-2026091902.pdf saved as Render-2026091902.pdf (works fine).

Since this happens during message ingestion at the Start Node trigger level (before process flow execution), is this a known issue or intended behavior related to document versioning suffixes?

Best answer by jayac0003

Yes, this behavior is expected due to how Appian’s underlying polling and custom email configurations handle special characters.

When configuring a process to start via an incoming email trigger, Appian parses the the incoming local mailbox alias strings. Appian expect incoming email to target a specific address structure format. Underscores( _ ) are stripped, truncated because Appian’s internal email listener infrastructure treats certain special characters as string delimiters or invalid components for specific process routing parameters.

To prevent this truncation and ensure reliable routing, you can use a Hyphen(- ) or switch to web API rather than relying on a legacy native email start node trigger a web hook that invokes the web API which then passes variables and kicks of process by a!startProcess() smart service.

1 reply

jayac0003
jayac0003Answer
New Participant
September 16, 2026

Yes, this behavior is expected due to how Appian’s underlying polling and custom email configurations handle special characters.

When configuring a process to start via an incoming email trigger, Appian parses the the incoming local mailbox alias strings. Appian expect incoming email to target a specific address structure format. Underscores( _ ) are stripped, truncated because Appian’s internal email listener infrastructure treats certain special characters as string delimiters or invalid components for specific process routing parameters.

To prevent this truncation and ensure reliable routing, you can use a Hyphen(- ) or switch to web API rather than relying on a legacy native email start node trigger a web hook that invokes the web API which then passes variables and kicks of process by a!startProcess() smart service.

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