Decrypt IMAP email?

I am receiving emails in my application through IMAP, and everything is showing up the right way except the text that is encrypted, how do I decrypt or configure it to not be encrypted ??

I am using the node-imap library to receive and the Mailparser to make the parse of the emails, however it is the first time that I am working with this question of emails and I do not have experience in the subject, who can help me, / p>

Part of one of the headers, all follow the same pattern:

{ attachments:
   [ { type: 'attachment',
       content: <Buffer ff d8 ff e0 00 10 4a 46 49 46 00 01 01 01 00 60 00 60 00 00 ff db 00 43 00 0a 07 07 09 07 06 0a 09 08 09 0b 0b 0a 0c 0f 19 10 0f 0e 0e 0f 1e 16 17 12 ... >,
       contentType: 'image/jpeg',
       release: null,
       filename: 'image001.jpg',

You are in base64:

 D7VuDOYyQMcCqllqbCwt3nEm+5yyfKcA4zjJPI6n8Kn09WgchyDHKuD/smpzplqiKiW6BVOVHp9PSuVzgk1NXPrcvhJUkox5Wt0/lqZ51rbFG4B4MZkYrwVb0Gc9qnuLq31e2e1jR2cjfGCMZIAJGfowqymn24GPJTHyjGPTp+WaSaOOyw9pB

But from what I saw I think it's the image of the email signature I received, as this signature contains an image. I'm kind of lost because I've never worked with it before ...