Allowed attachment file types

[ahargreaves_FW]

We have a simple Web AppBuilder template based viewer used for submitting redlines. Email messages are sometimes attached to these redlines by technicians and used for reference. However, when attempting to attach *.msg file types the error shown below is displayed. 

If the chosen file type, when uploading, is "all files *.*" why is this an issue?

[FaithSJohnson · Accepted solution]

I believe the problem is that .msg is not a supported attachment file type. This is the list of attachments allowed:

7Z, AIF, AVI, BMP, CSV, DOC, DOCX, DOT, ECW, EMF, EPS, GEOJSON, GIF, GML, GPKG, GTAR, GZ, IMG, J2K, JP2, JPC, JPE, JPEG, JPF, JPG, JSON, M4A, MDB, MID, MOV, MP2, MP3, MP4, MPA, MPE, MPEG, MPG, MPV2, PDF, PNG, PPT, PPTX, PS, PSD, QT, RA, RAM, RAW, RMI, SID, TAR, TGZ, TIF, TIFF, TXT, VRML, WAV, WMA, WMF, WMV, WPS, XLS, XLSX, XLT, XML, and ZIP.

(https://doc.arcgis.com/en/arcgis-online/reference/work-with-tables.htm#ESRI_SECTION2_3C99CF74A5C74A0...)

However, we have a really similar workflow and would like to be able to upload .msg files.