error in process filter: No email account found

Question

I use Emacs 27.1 (9.0) and mu4e 1.4.13 with multiple email accounts, and those email accounts have one main username and multiple aliases. Recently I started getting this error when replying to an email sent to an alias:

error in process filter: if: No email account found
error in process filter: No email account found

Before, I used to be able to reply to an alias and the reply would come from the main username.

How can I fix it?

Answer 1

I changed the name of the account from the capitalized name, which was on disk, to lowercase, and that caused the problem. Reverting it back to capitalized fixed it.

Problematic code:

(defvar my-mu4e-account-alist
  '(
    ("provider" ;; lower case!
     (mu4e-sent-folder "/Provider/Sent Items")
...

Fixed code:

(defvar my-mu4e-account-alist
  '(
    ("Provider" ;; capitalized!
     (mu4e-sent-folder "/Provider/Sent Items")
...