The value of the doSSL key, in the post to which you replied, was 'starttls'.

When you viewed this it wrapped, leaving one line ending with 'star, and the next line starting with a + (probably red unless you've changed your settings) to indicate wrapping, which was followed by the remainder of the value, i.e. ttls'.

As you have this in two code blocks, it does not appear to be a one-off typo. In both cases, you should have:

... doSSL => 'starttls', ...
[download]

You should not have:

... doSSL => 'star
+ttls', ...
[download]

I cannot comment on the validity of the parameters to Net::SMTPS->new(...); however, blindly copying that + is definitely wrong.

Edit (for clarity): s/on two lines/in two code blocks/