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Can't have equal signs (punctuations?) on local part

1796113 shared this problem 2 months ago


I'm using a home made method to generate a local part for each onine service provider, and the output is a base64-ed string. Then I ran into one ending in two equal signs ("=="), which is common for base64, but mailbox.org MX rejected that address, saying such address couldn't be found:


550 5.1.1 <Vc/Odg==@example.com> User doesn't exist: Vc/Odg==@example.com (in

    reply to RCPT TO command)`


But according to https://en.m.wikipedia.org/wiki/Email_address#Local-part , equal signs are permitted, along with punctuations like !#$%&'*+-/=?^_`{|}~ (I know the definite place to verify is the RFCs, but for my eyes' sake)

Further finding revealed that ending with one equal sign is the same. Meanwhile, a forward slash ("\") inside (not at ending) is OK.

Is this a configurable behavior? If not, would there be any documentation explaining what can and can not be in the local part?


Comments (1)


Wait... Is it that local parts can't have punctuations at their ending? So I must add some alphanumerics after them?