Email size limit settings

From MsgServerDocWiki

What settings are used to restrict the maximum email size?

UPDATE, 2/24/2010: This information has been moved to: http://wikis.sun.com/pages/viewpage.action?pageId=197660126. Refer to that page from now on.

A common problem experienced by email users is to have an email rejected due to the size of the email exceeding a user, group, domain, channel or MTA-wide level restriction e.g.

"SMTP Error: 5.3.4 a message size of 302 kilobytes exceeds the size limit of 300 kilobytes computed 
for this transaction"

Tracking down the particular setting which restricted the size to 300KB in the above example can be time-consuming due to the number of possible places where the limit can be set.

Messaging server minimises the size limit. For example if you had an overall MTA-wide limit of 10MB (BLOCK_LIMIT=10240 in option.dat) and a user-level limit set to 300KB ("mailMsgMaxBlocks: 300" in the users LDAP entry) then the smaller of the two limits will be enforced -- namely 300KB.

Messaging Server 6.3 implemented the ability to override channel and MTA level restrictions at a per-user level - RFE# 5104462 (LDAP_RECIPIENTLIMIT et al should override channel keyword and options).

Messaging server has no size-limits set by default.

[edit] Options

• MTA Level Options (option.dat): BLOCK_LIMIT
• Channel Level options (imta.cnf): blocklimit, sourceblocklimit
• User/Group level LDAP options (LDAP): mailMsgMaxBlocks, mailDomainMsgMaxBlocks, mgrpMsgMaxSize

[edit] Other considerations

• The LDAP_SOURCEBLOCKLIMIT option can be used to restrict the size of emails that users send. An example on how to use this option is provided here: http://forum.java.sun.com/thread.jspa?forumID=708&threadID=5164457

• If you are using Delegated Administrator to provision users and groups, note that each service packages will have a limit set by default. The following manual page provides a listing of the default limits for each service package e.g. "mars" has a "mailMsgMaxBlocks: 700" (700KB): http://wikis.sun.com/display/CommSuite/Service+Package+Details

• End-users often get confused between the maximum size limit for an email vs. the size of attachments. For example a user tries to send a 7MB document and the email gets rejected due to the email being over 10MB. The discrepancy is due to 8bit->7bit MIME encoding of the attachment. This conversion increases the size of the attachment (and thus the email) by ~33%

• Email clients such as UWC/Communications Express (CE) may impose their own restriction on the maximum size of an email and attachments (refer to the service.http.maxmessagesize and service.http.maxpostsize configutil settings).