PMDF System Manager's Guide

There is a limitation in VMS MAIL which prevents a foreign protocol transport, such as PMDF, from sending through VMS MAIL over DECnet to a remote VMS MAIL using block mode I/O. This restriction manifests itself as a problem when PMDF tries to deliver a message which contains very long records through a MAIL_ (MAIL-11) or D (DECnet) channel, or even through the L (local) channel if the recipient address has used MAIL-11 forwarding to forward their messages to another DECnet node.

If you find messages stuck in the message queue for the D channel, check the corresponding log file, e.g., d_master.log, for an error of the form

$ MAIL/PROTOCOL=PMDF_SHARE_LIBRARY %RMS-W-RTB, 397 byte record too large for user's buffer

The only solution to this problem is to mark your D channel with the linelength keyword to force PMDF to soft-wrap (by encoding) lines which exceed 255 characters. For example

d logging 733 linelength 255 DECNET-MAIL

See Section 2.3.4 for details on the linelength keyword.

If you see such an error for messages stuck for the L (local) channel, check whether the recipient has MAIL-11 forwarding set to another DECnet node. If so, encourage the recipient user to use PMDF style forwarding instead -- forwarding that will route through PMDF and thence through a D channel marked with the linelength keyword as described above. It is also possible to mark the L channel itself with the linelength keyword---but that will impact all your L channel users, not just those who forward their messages to other DECnet nodes. By having such users forward through PMDF and a D channel instead, you can restrict the cases where PMDF has to perform (encoding based) soft line wrapping to only those cases where it is strictly required.