We're not entirely sure why, but Chase has two different sets of email addresses that they will use when sending out email verification codes for account access.
If you request an email verification code when using Chase's website (www.chase.com) the verification code will be delivered from an @emailonline.chase.com email address.
If you request an email verification code when logging in to Chase's mobile application, the verification code will be delivered from an @acctmanagement.com email address.
We're not entirely sure why Chase does this. However, we can tell you that when Level connects to Chase on your behalf, the requests for an email verification code use the same gateway as the Chase mobile app - so the verification code emails will be delivered from an @acctmanagement.com address.
For those worried that those emails look suspicious, a whois lookup confirms that Chase does in fact own that domain: https://who.is/whois/acctmanagement.com/