There Are Surprising Restrictions to Pluses and Dots In Gmail Addresses

The internet has many resources (one, two, three) that mention that for receiving emails to your gmail address...

• Everything after plus sign (+) is ignored.
• Dots/periods (.) are ignored
• Example: e.x.a.m.p.l.e+asdf_1234@gmail.com will deliver to example@gmail.com

Note: many websites do not accept email addresses that include a plus sign (+), and I think basically all websites accept dots before the @.

There seems to be some restrictions on dots that are not discussed very much...

• Dots can not be consecutive; "e..xample@gmail.com" is not usable.
• Dot can not be the first character; ".example@gmail.com" is not usable.
• Dot can not be the last character; "example.@gmail.com" is not usable.
• The above dot restrictions apply even after a plus sign; "example+a..b@gmail.com" is not usable.