Local format restrictions MTA option

Alias and address MTA options:  (bitmask)
The   MTA option affects  whether the pipe character (vertical bar) may appear in local  (L) channel addresses. It also affects whether filename delivery format,     , is  permitted. Note that authenticated submissions bypass such restrictions.

In a configuration with   set  on the local (L) channel,  such as in normal Messaging Server MTA configuration,  this option is not really relevant: the    effect takes precedence in requiring that every local-part correspond  to an actual user -- unless the pipe character or a leading plus  character were to occur in a user&#x27;s e-mail address, these syntaxes  would inherently not correspond to actual user e-mail addressses and  hence not be permitted. But in a different sort of configuration, such as an old PMDF configuration, this option controls whether the special  syntaxes are allowed in addresses matching the local (L) channel. The default value is 1, meaning that (in the absence of   ), pipe characters are disallowed but  filename delivery is allowed.

Bit 0 is the least significant bit.

The error, if such a condition is violated (and with  not set), will be: 5.1.3 invalid material in localpart of address: address and as an SMTP error: 553 5.1.3 invalid material in localpart of address: address

See also:
 * Alias and address MTA options
 * viaaliasrequired Option
 * Local channel