Error: Invalid from email address - SendGrid

I've been using SendGrid.com to handle password reset email requests for a few years without issue. I haven't changed anything and for the last two days all users have been getting an "Error: Invalid from email address" error on all email requests.

This is happening on all valid email addresses.

For the life of me I cannot figure out why this would randomly start happening. SendGrid seems to be running without issue on their end. I am waiting to get feedback from Sendgrid.

My set up:

    var nodemailer = require('nodemailer');
    var sgTransport = require('nodemailer-sendgrid-transport');

    app.post('/forgot', usernameToLowerCase, function(req, res, next) {
    async.waterfall([
    function(done) {
    crypto.randomBytes(20, function(err, buf) {
    var token = buf.toString('hex');
    done(err, token);
    });
    },
    function(token, done) {
    User.findOne({ username: req.body.username }, function(err, user) {
    if (!user) {
    req.flash('error', 'No account with that email address exists.');
    return res.redirect('/forgot');
    }
    
    user.resetPasswordToken = token;
    user.resetPasswordExpires = Date.now() + 3600000; // 1 hour
    
    user.save(function(err) {
    done(err, token, user);
    });
    });
    },
    function(token, user, done) {
    
    
    var options = {
    auth: {
    api_user: '=====',
    api_key: '======'
    }
    }
    
    var client = nodemailer.createTransport(sgTransport(options));
    
    var email = {
    from: 'BusinessName',
    to: user.username,
    subject: 'Reset Your Password',
    text:'====='
    };
    
    client.sendMail(email, function(err) {
    req.flash('success', 'An email was sent to ' + user.username + ' with further instructions.' );
    done(err);
    });
    }
    ], function(err) {
    if (err) return next(err);
    res.redirect('/forgot');
    });
    });