gnus nnimap intermittent login failure

[Vivishek Sudhir <vivishek.sudhir@gmail.com>]

Hi, 

I've been using gnus to fetch/reply-to emails on my gmail via gnus'
in-built nniamp backend. The minimal working configuration (in my init.el) is as follows: 

(use-package gnus 
    :config 
    (require 'nnir) ; for searching through imap 

    (require 'epa-file) ; to be able to code/decode gpg files in emacs 
    (epa-file-enable) 
    (setq epa-pinentry-mode 'loopback 
          epa-file-cache-passphrase-for-symmetric-encryption t) 

    (require 'auth-source) ; setup gpg file access 
    (setq auth-sources '((:source "./authinfo.gpg"))) ; this is where to find the login details 

    ; set gmail as the primary source of incoming mail 
    (setq gnus-select-method 
          '(nnimap "gmail" 
                   (nnimap-address "imap.gmail.com") 
                   (nnimap-server-port 993) 
                   (nnimap-stream ssl) 
                   (nnir-search-engine imap) 
                   ) 
          ; ensure gnus doesnt ignore gmail folders 
          gnus-ignored-newsgroups "^to\\.\\|^[0-9. ]+\\( \\|$\\)\\|^[\”]\”[#’()]" 
          ; mark all sent messages as read 
          gnus-gcc-mark-as-read t 
          ) 

    ; configure sending email via gmail smtp, with starttls encryption 
    (setq message-send-mail-function 'smtpmail-send-it 
          smtpmail-starttls-credentials '(("smtp.gmail.com" 587 nil nil)) 
          smtpmail-auth-credentials '(("smtp.gmail.com" 587 "myemail@gmail.com" nil)) 
          smtpmail-default-smtp-server "smtp.gmail.com" 
          smtpmail-smtp-server "smtp.gmail.com" 
          smtpmail-smtp-service 587 
          starttls-use-gnutls t) 

      ; cache emails 
    (setq message-directory "~/gmail" 
          gnus-use-cache t 
          gnus-cache-directory "~/gmail/cache" 
          gnus-cache-enter-articles '(ticked dormant read unread) 
          gnus-cache-remove-articles nil 
          gnus-cacheable-groups "^nnimap" 
          gnus-keep-backlog 200 
          ) 

    ; set gnus parameters 
    (setq gnus-parameters 
      '((".*" 
         (gnus-use-scoring nil) 
         (expiry-wait . 2) 
         (display . all) 
         ))) 
    ; retrieve 100 newest messages from all groups by default 
    ; (setq gnus-parameter-large-newsgroup-initial-alist ((".*" . 100))) 
    (setq gnus-large-newsgroup 100) 
  ) 

There is also some buffer formatting settings I've omitted in the above. 

Essentially, the file authinfo.gpg contains my login credentials for
gmail's imap and smtp servers, which is read by gnus to log in to fetch/reply-to emails. 

The problem is that *sometimes* when I start gnus, things work
perfectly; but about 3 out of 5 times, it would get stuck and show
something like "IMAP user at gmail (default <myemail>):" on the
minibuffer, and if I do RET, it would ask for my password. It seems that
on these occasions, gnus doesn't read the authinfo.gpg file, and falls
back to asking me for the login credentials. 

Why is this happening, and how can this be solved? 

Thanks.