Alias_hash_size MTA option
Internal size MTA options:
alias_hash_size MTA option sets the size of the alias hash table. This in turn is an upper limit on the number of aliases that can be defined in the alias file, or equivalently the number of named alias groups in Unified Configuration. The default is 256; the maximum that the MTA will allow with normal, automatic resizing is 15,000 (controlled from the
maximum.dat file); the "hard" maximum value allowed is 1,000,000. Attempts to set this option higher than 1,000,000 will result in an mm_init error, "ALIAS_HASH_SIZE exceeds maximum". Attempts to specify more aliases in the alias file than allowed by this option's maximum (normally the automatic, resize maximum, unless a higher maximum has been explicited configured for this option) will result in an mm_init error, "no room in table for alias ...".