Uploading Mailing List Subscribers Using CSV Error on Build 9686 - 9714

Problem reported by Scarab - 8/13/2026 at 11:06 AM

Being Fixed

As of SmarterMail Enterprise Build 9686 our Mailing List Moderators have been reporting errors with uploading subscribers using CSV. They receive an "Error Uploading" and "An Unknown Error Occurred" messages. There is nothing in the Detailed SmarterMail logs or Detailed IIS logs.

Initially on Build 9686 SmarterMail Admins were able to work around this issue by uploading the CSV for them without error. However as of Build 9714 the errors "Error Uploading" and "An Unknown Error Occurred" have been happening even for SmarterMail Admins when uploading subscribers using a CSV file.

This has been happening to multiple domains and all CSV files have the first column titled as EmailAddress. We have tried multiple CSV files and even those with a solitary column are generating these errors.

So far it hasn't been a priority issue as you can still copypasta the Subscribers using [NEW] button. Definitely seems like a bug though. The last Build that uploading a CSV to Mailing List Subscribers functioned properly was Build 9623.

2 Replies

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Derek Curtis Replied

8/13/2026 at 12:23 PM

Employee Post

Thanks. We were able to confirm this.

Derek Curtis

CCO

SmarterTools Inc.

www.smartertools.com

Donald Bergeson Replied

8/17/2026 at 4:40 PM

Employee Post

Hello. We have been unable to replicate your issue with uploading mailing list subscribers with a CSV, and so we have opened up a ticket for further review and to gather a little more information from you.

Donald Bergeson
Software Developer
SmarterTools Inc.

www.smartertools.com

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