When you can't use a + use a .
Name@email.com is n.ame@email.com is n.a.me@email.com is n.am.e@email.com etc
Name@email.com is n.ame@email.com is n.a.me@email.com is n.am.e@email.com etc
e.g andrew@gmail.com, a.n.d.r.e.w@gmail.com and a.....ndrew@gmail.com all are the same user and will go into their mailbox (which I have used to avoid the + stripping that some sites do)
andrew@outlook.com and a.ndrew@outlook.com are two distinct users.
Obviously if you control the domain or use a provider who supports it you can add an alias with punctuation but then you might as well just use e.g ebay@c.com to track the email source.