Host hash size MTA option

Internal size MTA options:  (1-1000000)
The  MTA option controls the size of the channel hosts hash table. Each channel host  specified on a channel definition in the MTA configuration file (both official hosts and aliases) consumes one slot in this hash table, so the total number of channel hosts cannot exceed the value specified. The default is 512; the maximum allowed with normal, automatic resizing is 16384 (controlled from the  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, "HOST_HASH_SIZE exceeds maximum".

Attempts to specify more rewrite rules than allowed by this option&#x27;s maximum (normally the automatic resizing maximum, unless a higher maximum has been explicitly configured) will result in an mm_init error, "no room in channel host table for ...". In particular, note the following. In its literal meaning, the "no room in channel host table for ..." error indicates that your configuration&#x27;s current MTA internal table sizes are not large enough for the number of host names listed in your channel definitions. However, note that an extraneous blank line in the rewrite rules (upper portion) of your MTA configuration file causes the MTA to interpret the remainder of the configuration file as channel definitions; with just one such extraneous blank line, the MTA sees just one extra channel but with a lot of (all the rest of the rewrite rules as) host names on that channel. So check the line of the file that the error is complaining about: if it is not truly intended as a host name on a channel definition but rather is a line in the rewrite rules section of your configuration file, then check for an extraneous blank line somewhere above it.

See also:
 * Host name channel options
 * Internal size MTA options