IlohaMail should work with the default configuration of PHP, but here are some relevant options. All of these can be changed in the php.ini file.

Directive	Value	Description
short_open_tag	1	Required
file_uploads	1	Required for uploading attachments
post_max_size	size	This will also affect the maximum size of attachments (see below).
upload_max_filesize	size	Maximum size of uploaded attachments. Should be same as post_max_size